Hapten-carrier conjugates for use in drug-abuse therapy and methods for preparation of same

ABSTRACT

Hapten-carrier conjugates capable of eliciting anti-hapten antibodies in vivo by administering, in a therapeutic composition, are disclosed. Methods of preparing said conjugates and therapeutic compositions are also disclosed. Where the hapten is a drug of abuse, a therapeutic composition containing the hapten-carrier conjugate is particularly useful in the treatment of drug addiction, more particularly, cocaine addiction. Passive immunization using antibodies raised against conjugates of the instant invention is also disclosed. The therapeutic composition is suitable for co-therapy with other conventional drugs.

REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/563,673 filed Nov. 28, 1995, which is a continuation-in-partof U.S. patent application Ser. No. 08/414,971 filed Mar. 30, 1995.

FIELD OF THE INVENTION

The present invention relates to treatment of drug abuse. Morespecifically, the present invention relates to methods of treating drugabuse using drug/hapten-carrier conjugates which elicit antibodyresponses and/or using the antibodies to the drug/hapten-carrierconjugates.

BACKGROUND OF THE INVENTION

The prevalence of drug use and abuse worldwide, especially in the UnitedStates, has reached epidemic levels. There are a plethora of drugs, bothlegal and illegal, the abuse of which have become serious public policyissues affecting all strata of society with its obvious medical andsocial consequences. Some users live in an extremely high riskpopulation associated with poverty and illegal activity. Other users whomight classify themselves as recreational users are at risk due to (a)properties of the drug(s) which make them addictive, (b) apredisposition of user to become a heavy user or (c) a combination offactors including personal circumstances, hardship, environment andaccessibility. Adequate treatment of drug abuse, including polydrugabuse, requires innovative and creative programs of intervention.

Two especially problematic drugs of addiction are cocaine and nicotine.Cocaine is an alkaloid derived from the leaves of the coca plant(Erythroxylon coca). In the United States alone, there currently aremore than 5 million regular cocaine users of whom at least 600,000 areclassified as severely addicted (Miller et al. (1989) N.Y. State J. Med.pp. 390-395; and Carroll et al. (1994) Pharm. News. 1:11-16). Withinthis population, a significant number of addicts actively are seekingtherapy. For example, in 1990, 380,000 people sought medical treatmentfor cocaine addiction and the number is increasing. At that is time, itwas estimated that 100,000 emergency room admissions per year involvecocaine use. The cumulative effects of cocaine-associated violent crime,loss in individual productivity, illness, and death is an internationalproblem.

The lack of effective therapies for the treatment of cocaine addictionstrongly suggests that novel approaches must be developed. Additionalfactors contributing to the lack of successful treatment programs isthat patterns of cocaine abuse have varied with time. In an articleentitled “1994 Chemical Approaches to the Treatment of Cocaine Abuse”(Carroll et al. (1994) Pharm. News, Vol. 1, No. 2), Carroll et al.report that since the mid-1980's, intravenous and nasal dosing of thehydrochloride salt (coke, snow, blow) and smoking of cocaine free-base(crack) have become common routes of administration, producing euphoriaand psychomotor stimulation which last 30-60 minutes. Unlike some otherabused drugs, cocaine can be taken in binges lasting for several hours.This behavior leads to addiction, and in some cases, to toxicconsequences (Carroll et al., Pharm. News, supra.).

There are only very limited treatments for drugs of abuse and noeffective long term treatments for cocaine addiction. Treatmentsinclude, but are not limited to, counseling coupled with theadministration of drugs that act as antagonists at the opioid receptorsor drugs that try to reduce the craving associated with drug addiction.One approach to treatment is detoxification. Even temporary remissionswith attendant physical, social and psychological improvements arepreferable to the continuation or progressive acceleration of abuse andits related adverse medical and interpersonal consequences (Wilson etal. in Harrison's Principle of Internal Medicine Vol. 2, 12th Ed.,McGraw-Hill (1991) pp. 2157-8). More specifically, is pharmacologicalapproaches to the treatment of cocaine abuse generally involve the useof anti-depressant drugs, such as desipramine or fluoxetine which mayhelp manage the psychological aspects of withdrawal but, in general, donot directly affect the physiology of cocaine. (Kleber (1995) ClinicalNeuropharmacology 18:S96-S109). Further, their effectiveness varieswidely (Brooke et al. (1992) Drug Alcohol Depend. 31:37-43). In somestudies, desipramine reduced self-administration (Tella (1994) Collegeon Problems of Drug Dependence Meeting Abstracts; Mello et al. (1990) J.Pharmacol. Exp. Ther. 254:926-939; and Kleven et al. (1990) Behavl.Pharmacol. 1:365-373), but abstinence rate following treatment did notexceed 70% (Kosten (1993) Problems of Drug Dependence, NIDA Res. Monogr.85). There has also been the use of drugs which potentiate dopaminergicn transmission, such as bromocriptine, but the benefits of such drugsare limited in part by toxicity (Taylor et al. (1990) West. J. Med.152:573-577). New drugs aimed at replacing methadone for opioidaddiction, such as buprenorphine, have also been used based oncross-interference with the dopaminergic system, however only limitedclinical study information is available (Fudula et al. (1991) NIDAResearch Monograph, 105:587-588). Buprenorphine has been reported todecrease cocaine self-administration (Carroll et al. (1991)Psychopharmacology 106:439-446; Mello et al. (1989) Science 245:859-862;and Mello et al. (1990) J. Pharmacol. Exp. Ther. 254:926-939); however,cocaine abstinence rates following treatment generally do not exceed 50%(Gastfried et al. (1994) College on Problems of Drug Dependence MeetingAbstracts; and Schottenfeld et al. (1993) Problems on Drug Dependence,NIDA Res. Monogr. 311).

Present therapies used to treat cocaine addicts have at least four majorlimitations leading to a very high rate of recidivism. First, andperhaps most fundamentally, the is contributing neurochemical events incocaine abuse and addiction are complex (Carroll et al. (1994) supra.).As a result, single acting neuropharmacological approaches, such asinhibition of dopamine uptake, do not appear to be sufficient toovercome addiction. Second, the drugs currently used in cocaineaddiction treatments have significant side-effects themselves, limitingtheir utility. Third, drug therapy compliance is problematic among thispatient population. Current therapies can require frequent visits to ahealth care provider and/or self-administration of drugs designed tocure the addict of his habit. Because many of these drugs prevent theeuphoria associated with cocaine, there is a strong disincentive totaking the drug. (Carroll, et al. (1994) supra.; Kosten et al. (1993)Problems of Drug Dependence, NIDA Res. Monogr. 132:85; Schottenfeld etal. (1993) Problems of Drug Dependence, NIDA Res. Monogr. 132:311.)Fourth, because of the complex chemistries involved in pharmacologicaltherapies, many of them may be incompatible with other therapiescurrently in use or in clinical trials. Finally, most of thepharmacotherapy studies have been administered in context oflow-intensity outpatient treatment programs and have not been linkedwith intensive outpatient treatment or other psychosocial treatment thatappears necessary for successful management of cocaine dependentpatients. (Rao (1995) Psychiatric Annuls 25(6):363-368).

Nicotine (1-Methyl-2-(3-pyridyl)pyrrolidine) is an alkaloid derived fromthe tobacco leaf. Nicotine use is widespread throughout the world and islegally available in many forms such as cigarettes, cigars, pipetobacco, and smokeless (chewing) tobacco. Although the addictive natureof nicotine and the dangers of smoking have been known for many years(Slade et al. (1995) JAMA 274(3):225-233), cigarette smoking remainspopular. An estimated 51 million Americans smoke and, according to theCenter for Disease is Control and Prevention, 420,000 people each yeardie from smoking related disorders.

The most popular nicotine delivery system is the cigarette. Cigarettescontain 6 to 11 mg of nicotine, of which the smoker typically absorbs 1to 3 mg. The typical pack-per-day smoker absorbs 20 to 40 mg of nicotineeach day, achieving plasma concentrations of 25 to 50 ng per milliliter.The plasma half life of nicotine is approximately two hours; the halflife of the major metabolite cotinine is 19 hours. (Henningfield (1995)The New England Journal of Medicine 333(18):1196-1203).

Since nicotine is legally and widely available there is relatively lowpressure against its use, unlike cocaine. Although a large percentage ofaddicted smokers have expressed a desire to stop smoking, and manyactually try to stop, only 2 to 3 percent of smokers become nonsmokerseach year. (Henningfield (1995) supra.). The high rate of recidivism insmokers who try to quit is indicative of the strong effect of nicotinedependence. (O'Brien et al. (1996) Lancet 347:237-240).

Nicotine addiction is a chronic, relapsing disorder. Nicotine targetsthe mesolimbic reward system eventually resulting in physiologicaldependence. Evidence suggests that nicotine binds to the α-subunit ofthe nicotinic acetylcholine receptors in the central and peripheralnervous systems resulting in increased dopamine release. It is thoughtthat increased numbers of nicotinic acetylcholine receptors in the brainenhance the physiological dependence of nicotine (Balfour (1994)Addiction 89:1419-1423). These physiological effects of nicotine arepowerful reinforcers of the psychological addiction. The nicotine usersincreased cognition and improved mood, as well as the negative effectsassociated with abstinence (i.e., is withdrawal symptoms), serve aspowerful motivators for continued tobacco use.

The lack of effective therapies for nicotine dependence and the poorrate of success in those who try and quit its use indicate that there isa strong need for a new therapy. Currently, the two most populartherapies are nicotine polacrilex (“nicotine gum”) andtransdermal-delivery systems (“nicotine patch”). These “replacementmedications” act to deliver low amounts of nicotine to the user over aperiod of time to slowly wean the nicotine user off the drug. It isthought that these methods reduce withdrawal symptoms and provide someeffects for which the user previously relied on cigarettes (such asdesirable mood and attentional states). (Henningfield (1995) supra.).These methods, however, n suffer from the drawbacks of low penetranceand recidivism of the non-motivated quitter. Moreover, negative effectshave been reported by users of nicotine gum such as mouth irritation,sore jaw muscles, dyspepsia, nausea, hiccups and paresthesia. Reportedadverse effects from the nicotine patch include skin reactions (itchingor erythema), sleep disturbance, gastrointestinal problems, somnolence,nervousness, dizziness and sweating (Haxby (1995) Am. J. Health-Syst.Pharm. 52:265-281).

Experimental diagnostic approaches and therapies for treating drugaddiction have been suggested in the literature which have yet to bepracticed. For example, vaccination as a therapeutic approach for drugaddiction has been described previously in principle. Bonese et al.investigated changes in heroin self-administration by a rhesus monkeyafter immunization against morphine (Bonese et al. (1974) Nature 252:708-710). Bagasra et al. investigated using cocaine-KLH vaccination as ameans to prevent addiction (Immunopharmacol. (1992) 23:173-179),although no conclusive results are produced and the methods used byBagasra are in dispute. (Gallacher (1994) Immunopharm. 27:79-81).Obviously, if a conjugate is to be effective in a therapeutic regimen,it must be capable of raising antibodies that can recognize free cocaineor nicotine circulating in vivo. Cerny (WO 92/03163) describes a vaccineand immunoserum against drugs. The vaccine is comprised of a haptenbonded to a carrier protein to produce antibodies. Also disclosed is theproduction of antibodies against drugs, and the use of these antibodiesin the detoxification of one who has taken the drug. Carrera et al.,Nature 378:727-730 (1995) discloses the synthesis of a cocaine-KLHvaccine to induce anti-cocaine antibodies which block the locomotoreffects of the drug in rats. Blincko, U.S. Pat. No. 5,256,409, disclosesa vaccine comprising a carrier protein bound to one hapten from thedesipramine/30 imipramine class of drugs and another hapten from thenortriptyline/amitriptyline class of drugs. Liu et al., U.S. Pat. No.5,283,066, discloses use of a hapten-polymeric solid support complex toinduce an immune response.

Passive administration of monoclonal antibodies to treat drug abuse hasbeen previously described (see, Killian et al. (1978) Pharmacol.Biochem. Behavior 9:347-352; Pentel et al. (1991) Drug Met. Dispositions19:24-28). In this approach, pre-formed antibodies to selected drugs arepassively administered to animals. While these data provide ademonstration of the feasibility of immunological approaches toaddiction therapy, passive immunization as a long term human therapeuticstrategy suffers from a number of major drawbacks. First, if antibodiesto be used for passive therapy are from non-human sources or aremonoclonal antibodies, these preparations will be seen as foreignproteins by the patient, and there may be a rapid immune response to theforeign antibodies. This immune response is may neutralize the passivelyadministered antibody, blocking its effectiveness and drasticallyreducing the time of subsequent protection. In addition,readministration of the same antibody may become problematic, due to thepotential induction of a hypersensitivity response. These problems canbe overcome by production of immune immunoglobulin in human donorsimmunized with the vaccine. This approach is discussed in more detail inthe Examples. Second, passively administered antibodies are clearedrelatively rapidly from the circulation. The half life of a givenantibody in vivo is between 2.5 and 23 days, depending on the isotype.Thus, when the antibodies are passively administered, rather thaninduced by immunization, only short term effectiveness can be achieved.

Another immunological approach to drug addiction has been to use acatalytic antibody which is capable of aiding hydrolysis of the cocainemolecule within the patient (Landry et al. (1993) Science259:1899-1901). The catalytic antibody is generated by immunization ofan experimental animal with a transition state analog of cocaine linkedto a carrier protein; a monoclonal antibody is then selected that hasthe desired catalytic activity. Although this approach is attractivetheoretically, it also suffers from some serious problems. Catalyticantibodies must be administered passively and thus suffer from all ofthe drawbacks of passive antibody therapy. Active immunization togenerate a catalytic antibody is not feasible, because enzymaticactivity is rare among antibodies raised against transition stateanalogs, and activity does not appear to be detectable in polyclonalpreparations. In addition, the general esterase-like activity of suchcatalytic antibodies and the uncontrolled nature of the active immuneresponse in genetically diverse individuals makes them potentially toxicmolecules, particularly when they are being produced within a humanpatient.

Yugawa et al. (EP 0 613 899 A2) suggest the use of cocaine-proteinconjugate containing a cocaine derivative for raising antibodies for thedetection of cocaine or cocaine derivatives in a blood sample. The Syvapatents (U.S. Pat. No. 3,888,866, No. 4,123,431 and No. 4,197,237)describe conjugates to raise cocaine antibodies for immunoassays.Disclosed are conjugates to BSA using diazonium salts derived frombenzoyl ecgonine and cocaine. Conjugates are made using para-imino esterderivatives of cocaine and norcocaine to conjugate a carrier. Biosite(WO 93/12111) discloses conjugates of cocaine using the para-position ofthe phenyl ring of various cocaine derivatives increasing stability tohydrolysis by introducing an amide bond. The Strahilevitz patents (U.S.Pat. No. 4,620,977; n U.S. Pat. No. 4,813,924; U.S. Pat. No. 4,834,973;and U.S. Pat. No. 5,037,645) disclose using protein conjugates ofendogenous substances and drugs for treatment of diseases, preventingdependence on psychoactive haptens, as well as for use in immunoassays,immunodialysis and immunoadsorption.

Bjerke et al. (1987) Journal of Immunological Methods 96:239-246describes the use of a conjugate of cotinine 4′-carboxylic acid boundcovalently to poly-L-lysine to generate antibodies to the nicotinemetabolite cotinine for use in determining the presence of cotinine inphysiological fluids. Additionally, Abad et al. (1993) Anal. Chem.65(22):3227-3231 describe the use of 3′-(hydroxymethyl)nicotinehemisuccinate conjugated to BSA to generate antibodies to nicotine foruse in an ELISA used to measure nicotine in smoke condensates ofcigarettes. Neither reference, however, teaches or suggests the use of anicotine-carrier conjugate for use as a vaccine against nicotine abuse.

No effective therapy for drug addiction, especially, cocaine andnicotine addiction, has been developed. Thus, there is a need to developa long term treatment approach to drug addiction, in particular cocaineand nicotine addiction, which does not depend totally on the addictedindividual for compliance and self-administration.

SUMMARY OF THE INVENTION

The present invention overcomes the above mentioned drawbacks andprovides methods for treating drug abuse. Using therapeuticcompositions, in particular hapten-carrier conjugates, the presentinvention elicits an immune response in the form of anti-drug antibodieswithin the addict which upon subsequent exposure to the drug in avaccinated individual neutralizes the drug so the expectedpharmacological effects are diminished, if not eliminated. The presentinvention provides a therapeutic for drug addiction, particularlycocaine and nicotine addiction, based on vaccination of subjects with adrug/hapten-carrier conjugate, and more particularly, a cocaine-proteinor nicotine-protein conjugate. Therapeutic compositions of the inventioncomprise at least one hapten and at least one T cell epitope-containingcarrier which when conjugated to form a hapten-carrier conjugate iscapable, of stimulating the production of anti-hapten antibodies. Thehapten can be a drug or drug derivative, particularly cocaine ornicotine. When the therapeutic composition containing thedrug/hapten-carrier conjugate is administered to an addicted individual,anti-drug antibodies specific to the drug are elicited. A therapeuticimmunization regimen elicits and maintains sufficiently high titers ofanti-drug antibodies, such that upon each subsequent exposure to thedrug during the period of protection provided by the therapeutic,anti-drug antibodies neutralize a sufficient amount of the drug in orderto diminish, if not eliminate, the pharmacological is effect of thedrug. Also provided are novel methods of preparing these conjugates. Amethod of passive immunization is also provided, wherein a subject istreated with antibodies generated in a donor by vaccination with theHapten-carrier conjugate of the invention.

These and other features, aspects and advantages of the presentinvention will become more apparent and better understood with regard tothe following drawings, description, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic representation of the structural formula ofcocaine.

FIG. 1 b is a diagram representing sites of variability when preparing acocaine conjugate of the instant invention. The sites of variability arearbitrarily assigned to easily designate the compound and conjugates ofthe instant invention and not necessarily reaction sites.

FIG. 2 a is a representation of a number of possible, arbitrarilylabelled, “branches” of a hapten-carrier conjugate identified for easeof understanding suitable is compounds and conjugates used in thepractice of the instant invention.

FIG. 2 b is a representation of a number of possible, arbitrarilylabelled, “branches” of a hapten-carrier conjugate identified for easeof understanding suitable compounds and conjugates used in the practiceof the instant invention, wherein Q′ is a modified T-cellepitope-containing carrier, such as a modified protein carrier.

FIG. 3 a is a representation of 6 cocaine conjugates (PS-2, PS-3, PS-4,PS-5, PS-6, and PS-9) of the instant invention, where Q is a T cellepitope-containing carrier such as a carrier protein or modified T cellepitope-containing carrier such as a modified carrier protein.

FIG. 3 b is a representation of “branches” at the sites of variabilityoff the tropane ring of cocaine of the cocaine conjugates andintermediates of the instant invention.

FIG. 4 is a representation of “branches” at the sites of variability offthe tropane ring in FIG. 1 b of four compounds useful in preparing theconjugates of the instant invention.

FIG. 5 is a representation of the structures of five reagents useful inthe practice of the instant invention.

FIG. 6 is a representation of the structures of four alternative drugsof abuse suitable for conjugation and administration in accordance withthe teachings of the instant invention.

FIG. 7 is a schematic diagram representing two possible conjugationreactions to prepare a single cocaine conjugate (PS-5) according to themethods of the instant is invention.

FIG. 8 is a representation of the structures of “succinylatednorcocaine” and “pre-activated succinylated norcocaine” useful in thepreparation of some of the conjugates of the instant invention.

FIG. 9 a is a graph showing the IgG antibody response in mice immunizedwith cocaine conjugate (PS-5.1/0.6+CFA i.p.) of the instant invention.The antibody response is detected by in vitro binding to the appropriateHEL conjugate made using HEL rather than BSA as a carrier. Mice received2 injections of 50 μg per injection. The curves represent the responseof 5 individual mice per group.

FIG. 9 b is a graph showing the IgG antibody response in mice immunizedwith cocaine conjugate (PS-5.5 Alum i.p.) of the instant invention. Theantibody response is detected by in vitro binding to the appropriate HELconjugate made using HEL rather than BSA as a carrier. Mice received 2injections of 50 μg per injection. The curves represent the response of5 individual mice per group.

FIG. 9 c is a graph showing the IgG antibody response in spice immunizedwith cocaine conjugate (PS-9.2+CFA i.p.) of the instant invention. Theantibody response is detected by in vitro binding to the appropriate HELconjugate made using HEL rather than BSA as a carrier. Mice received2-injections of 50 μg per injection. The curves represent the responseof 5 individuals mice per group.

FIG. 10 a is a graph demonstrating that antiserum binding to acocaine-protein conjugate can be competed off using free cocaine.

FIG. 10 b is a bar graph showing that immune antiserum can bind³H-cocaine.

FIG. 11 a is a bar graph illustrating that a cocaine-BSA conjugateprepared according to the method of the instant invention providetwo-fold protection in high dose cocaine LD₅₀

FIG. 11 b is another bar graph illustrating that a cocaine-BSA conjugateprepared according to the method of the instant invention providetwo-fold protection in high dose cocaine LD₅₀

FIG. 12 a is a representation of a gel showing the relative molecularweights of native (monomer and pentamer) and recombinant cholera toxin-B(CTB) (monomer).

FIG. 12 b is a representation of a gel illustrating the stability of CTBpentamers over a pH range of 3-9.

FIG. 12 c is a drawing of a Western Blot gel showing peak fractionsrCTB#32 and rCTB#53 which were obtained by periplasmic expressionresulting in pentameric CTB.

FIG. 13 a is a graph representing an ELISA where the anti-CTB antibodydetects the ability of rCTB to bind to ganglioside GM1 on the ELISAplate.

FIG. 13 b is a scan depicting a flow cytometry binding assay in whichrCTB is bound to eukaryotic cells expressing ganglioside GM1.

FIG. 14 a is a graph representing an ELISA in which native CTB andcocaine-CTB conjugate CTB-5.8 (PS-5.8 conjugated to CTB) are shown to bepentameric, based on their ability to bind to ganglioside GM1.

FIG. 14 b is a graph representing an ELISA in which CTB-5.8 (PS-5.8conjugated to CTB) is bound to ganglioside GM1 and the conjugate isdetected with an anti-cocaine (anti-benzoylecgonine) monoclonalantibody.

FIG. 15 is a schematic representation of another reaction useful in thepreparation of conjugates of the instant invention, in particular, 3benzoate ester adduct 4.

FIG. 16 is a schematic representation of the synthesis of a carbon-13labelled conjugate.

FIG. 17 a is a schematic representation of the structural formula ofnicotine.

FIG. 17 b is a diagram representing sites of variability when preparinga nicotine conjugate of the instant invention. The sites of variabilityare arbitrarily assigned to easily designate the compound and conjugatesof the instant invention and not necessarily reaction sites. These sitesof variability are as referred to in FIG. 18.

FIG. 18 is a representation of “branches” at the sites of variabilityoff the nicotine molecule for nicotine conjugates and intermediates ofthe instant invention. Nicotine conjugates of the present invention arerepresented when Q is a T cell epitope containing carrier.

FIG. 19 is a representation of nicotine metabolites useful inpreparation of some of the conjugates of the present invention.

FIG. 20 shows succinyl norocaine consisting of a mixture of at least twoisomers; namely the exo and endo forms of the succinyl group.

FIG. 21 shows results of ¹H-NMR analysis demonstrating that the ratio ofexo:endo for succinyl norcocaine is dependent upon the dielectricconstant (c) of the solvent used.

FIG. 22 shows the proposed basis for the marked increase in stability ofnorcocaine over cocaine, which may be thought of as being due to theinability of the tropane nitrogen to stabilize the hydrolysisintermediate.

FIG. 23 shows results of testing of different drugs at varyingconcentrations for their ability to inhibit the binding of antibodies tococaine-HEL. The panel of drugs tested included cocaine, benzoylecgonine(the major metabolite of cocaine); dopamine, serotonin, andnorepinephrine (neurotransmitters); methylphenidate and amphetamine (CNSstimulators); procainamide HCl (a cardiac depressant); atropine (acompound that has a tropane ring in its structure); and lidocaine (ageneral anesthetic). The pool of anti-cocaine antisera was specific forcocaine in that cocaine competed with the cocaine-HEL conjugate forbinding to the antibodies.

FIG. 24 shows results of testing of mouse sera in an ELISA for antibodybinding to a conjugate of PS-55 and hen egg lysozyme protein (HEL). Themice had been immunized with a nicotine-BSA conjugate.

FIG. 25A-C shows that in sera from mice which were injected with PS-55BSA, antibody binding to PS-55 HEL was inhibited by free nicotine.

FIG. 26 shows results of testing in an ELISA using plates coated withPS-5.4 conjugated to HEL (hen egg lysozyme) sera from Wistar male ratswhich were immunized with 10 ug of cocaine-rCTB conjugate precipitatedon alum intramuscularly and again bled 14 days after the secondinjection.

FIG. 27 shows results of a test to directly determine whether theantibodies generated in rats are capable of recognizing the free cocainemolecule, using a competition ELISA.

DETAILED DESCRIPTION OF THE INVENTION

The patent and scientific literature referred to herein establishes theknowledge that is available to those skilled in the art. The issued U.S.patents, PCT publications, and other publications cited herein arehereby incorporated by reference.

The present invention provides a therapeutic for drug addiction, basedon vaccination of an addicted individual with a drug/hapten-carrierconjugate, and more particularly, a cocaine-protein conjugate or anicotine-protein conjugate. Therapeutic compositions of the inventioncomprise at least is one hapten and at least one T cell epitopecontaining carrier which when conjugated to form a hapten-carrierconjugate is capable of stimulating the production of anti-haptenantibodies. As used herein the term “T cell epitope” refers to the basicelement or smallest unit of recognition n by a T cell receptor, wherethe epitope comprises amino acids essential to receptor recognition.Amino acid sequences which mimic those of the T cell epitopes and whichmodify the allergic response to protein allergens are within the scopeof this invention. A “peptidomemetic” can be defined as chemicalstructures derived from bioactive peptides which imitate naturalmolecules. The hapten can be a drug such as cocaine, nicotine or drugderivative.

When the therapeutic composition containing the hapten/m drug (orderivative thereof) is administered to the addicted individual,anti-drug antibodies specific to the drug are elicited. A therapeuticimmunization regimen elicits and maintains sufficiently high titers ofanti-drug antibodies, such that upon subsequent exposure to the drug,neutralizing antibodies attach to a sufficient amount of the drug inorder to diminish, if not eliminate, the pharmacological effects of thedrug. For example, when the therapeutic composition is a cocaine-carrierconjugate, treatment induces an anti-cocaine antibody response which iscapable of reducing or neutralizing cocaine in the bloodstream ormucosal tissue of a subject, thereby blocking the psychologicallyaddictive properties of the drug. Since in the present invention delayedor reduced levels of the drug of abuse reach the central nervous system,the addict receives diminished or no gratification from the use ofcocaine. This same mechanism of action, when administering anicotine-carrier conjugate, will induce anti-nicotine antibodies anddiminish or extinguish the gratification from the use of nicotine. Noside effects are expected from the administration of the therapeutic ofthe instant invention. For example, the instant drugs-of-abuse are smalland monovalent and so are not able to cross-link antibody. Therefore,formation of immune complexes and the associated pathologies are notexpected to occur after exposure to the drug of abuse. It is now, and isexpected to be, compatible with current and future pharmacologicaltherapies. Further, effective neutralization is long lasting. Forexample, neutralizing antibody responses against pathogens are known tolast for years. Accordingly, it is expected that high-titer anti-drugantibodies elicited using the therapeutic composition of the instantinvention can be maintained for long periods of time and possibly, atleast a year. This long-term effect of the therapeutic composition withreduced compliance issues reduces recidivism which is a problem withcurrent therapies.

Additionally, the therapeutic vaccination approach of the presentinvention to cocaine addiction is compatible with other therapiescurrently in use or in clinical trials. In fact, early phase co-therapyis highly desirable because of the time necessary to achieve optimalantibody titers. A number of diverse pharmacological agents would besuitable as co-therapies in preventing cocaine relapse, for example,desipramine, buprenorphine, naloxone, halperidol, chiorproazine,bromocriptine, ibogaine, mazindol, as well as others that may becomerelevant.

Similarly, the therapeutic vaccination approach of the present inventionto nicotine addiction is compatible with other therapies for minimizingsymptoms of nicotine withdrawal. For example, the nicotine-carrierconjugate of the present invention may be used in conjunction withclonidine, buspirone, and/or antidepressants or sedatives. The vaccineproduced by this approach will be compatable with the current nicotinereplacement therapies, i.e., gums and patches. Since anti-nicotineantibodies would take several weeks to be generated, some level ofcraving control would be provided by the use of nicotine replacementtherapies.

The following are terms used herein, the definitions of which areprovided for guidance. As used herein a “hapten” is alow-molecular-weight organic compound that reacts specifically with anantibody and which is incapable of inciting an immune response by itselfbut is immunogenic when complexed to a T cell epitope-containing carrierforming a hapten-carrier conjugate. Further, the hapten is characterizedas the specificity-determining portion of the hapten-carrier conjugate,that is, it is capable of reacting with an antibody specific to thehapten in its free state. In a non-immunized addicted subject, there isan absence of formation of antibodies to the hapten. The therapeuticcomposition is used to vaccinate individuals who seek treatment foraddiction to drugs. In the instant invention, the term hapten shallinclude the concept of a more specific drug/hapten which is a drug, ananalog of a portion of the drug, or drug derivative. The therapeuticcomposition, or therapeutic anti-drug vaccine, when initiallyadministered will give rise to a “desired measurable outcome”.Initially, the desired measurable outcome is the production of a hightiter of anti-drug antibodies (approximately 0.1 mg/ml to 1 mg/ml ofspecific antibody in the serum). However, manipulation of the dosageregimen suitable for the individual gives and maintains a sustaineddesired therapeutic effect. The “desired therapeutic effect” is theneutralization of a sufficient fraction of free drug of abuse to reduceor eliminate the pharmacological effects of the drug within atherapeutically acceptable time frame by anti-drug antibodies specificfor the drug upon a subsequent exposure to the drug. Determining thetherapeutically acceptable time frames for how long it takes to get asufficient antibody response to a given drug and how-long that antibodyresponse is maintained thereto are achieved by those skilled in the artby assessing the characteristics of the subject to be immunized, drug ofabuse to be neutralized, as well as the mode of administration. Usingthis and other vaccination protocols as a model, one skilled in that artwould expect the immunity or the period of protection to last severalmonths, up to more than one year.

“Passive immunization” is also disclosed which encompassesadministration of or exposure to intact anti-drug antibody or polyclonalantibody or monoclonal antibody fragment (such as Fab, Fv, (Fab′)2 orFab′) prepared using the novel conjugates of the instant invention. Asstated above, passive immunization of humans with an anti-cocaine oranti-nicotine antibody of the present invention as a n stand-alonetreatment may be less useful than active immunization. Passiveimmunization would be particularly useful as an initial co-treatmentand/or a supplementary complementary treatment (for example, during theperiod of time after initial administration of the vaccine but beforethe body's own production of antibodies) or in acute situations toprevent death (for example, when a person presents with a drugoverdose). In some situations, passive therapy alone may be preferable,such as when the patient is immunocompromised or needs a rapidtreatment.

The drug-conjugates of the present invention, as well as thecompositions of the present invention, may also be used as aprophylactic. That is, the drug-conjugates or compositions may beadministered to a mammal prior to any exposure to the drug to generateanti-drug antibodies. The generated anti-drug antibodies would bepresent in the mammal to bind to any drug introduced subsequent to theadministration of the conjugate or composition, and therefore minimizeor prevent the chance of becoming addicted to the drug.

The therapeutic composition of the instant invention, and morespecifically, the therapeutic anti-drug vaccine, is a compositioncontaining at least one drug/hapten-carrier conjugate capable ofeliciting the production of a sufficiently high titer of antibodiesspecific to the drug/hapten such that upon subsequent challenge with thedrug/hapten said antibodies are capable of reducing the addictiveproperties of the drug. The expected immune response to a hapten-carrierconjugate is the formation of both anti-hapten and anti-carrierantibodies. The therapeutic level is reached when a sufficient amount ofthe anti-drug specific antibodies are elicited and maintained to mount aneutralizing attack on drug introduced after vaccination. Thetherapeutic regimens of the instant invention allow for sufficient timefor production of antibodies after initial vaccination and any boosting.Further, the optimal anti-drug vaccine contains at least one drug/haptencarrier conjugate comprising an optimal combination of the drug ashapten and a carrier so that production of anti-drug antibodies iscapable of achieving an optimal therapeutic level, that is, remaining invivo at a sufficiently high titer to withstand a subsequent challengewithin several months with the selected drug. More particularly, theantibody titers remain sufficiently high to provide an effectiveresponse upon subsequent exposure to the drug for about two months toabout one year or more depending upon the individual, more usually atleast three months. This optimal composition consists of ahapten-carrier conjugate, excipients and, optionally adjuvants.

When used in the treatment of cocaine, the present invention defines ahapten-carrier conjugate, wherein the hapten is cocaine or a cocainederivative, which can be used to immunize mammals, particularly humans,to elicit anti-cocaine antibodies capable of binding free drug andpreventing transit of the drug to the reward system in the brain therebyabrogating addictive drug-taking behavior. It is believed that cocaineaffects the neuronal uptake of dopamine, norepinephrine, and serotonin.While not intending to exclude other modes of action, it is believedthat once cocaine enters the blood stream following inhalation (snortingor smoking) or intravenous administration, it rapidly crosses theblood-brain barrier where the intact cocaine binds to specificrecognition sites located on the dopamine transporter ofmesolimbocortical neurons, thereby inhibiting dopamine reuptake intopresynaptic neurons. The euphoric rush is due to rapid build-up ofdopamine in the synapse. The rapid action of cocaine presents problemsunique to cocaine therapy. For this reason, cocaine remains the mostcomplex and n challenging, and before the present invention, elusivedrug for which therapy is sought. Although estimates vary, it isbelieved that following intranasal administration, changes in mood andfeeling states are perceived within about 2 to 5 minutes, and peakeffects occur at 10 to 20 minutes. Thus, n the active ingredient, thehapten-carrier conjugate, must be capable of eliciting fast-actingantibodies. Cocaine free-base, including the free-base prepared withsodium bicarbonate (crack), has a relatively high potency and rapidonset of action, approximately 8 to 10 seconds following smoking. Anembodiment of the instant invention elicits antibodies capable ofrapidly and specifically neutralizing cocaine within this time frame.Due to the route of the circulation, i.v. cocaine is intermediate intime of onset of euphoria taking from about 30 seconds to about 1minute. Thus, when used in the treatment of cocaine abuse, thetherapeutic hapten-carrier conjugate composition of the instantinvention induce anti-cocaine antibodies which alter the physiologicalresponse to cocaine in humans. These antibodies possess the appropriatebioavailability and speed is of binding that is required to neutralizecocaine in vivo. The Examples herein describe experiments done in miceto simulate alteration of response in mammals.

When used in the treatment of nicotine, the present invention defines ahapten-carrier conjugate, wherein the hapten is nicotine or a nicotinederivative, which can be used to immunize mammals, particularly humans,to elicit anti-nicotine antibodies capable of binding free drug andpreventing transit of the drug to the reward system in the brain therebyabrogating addictive drug-taking behavior (e.g., smoking cigarettes). Itis believed that nicotine binds to the a-subunit of the nicotinicacetylcholine receptors in the brain which results in an increase indopamine release. It is thought that increased numbers of nicotinicacetylcholine receptors in the brain enhance the physiologicaldependence of nicotine. As discussed above in relation to cocaine,anti-nicotine antibodies would presumably limit the distribution ofnicotine across the blood-brain barrier to the brain, thus reducing itspharmacological effects. Antibody intervention in the case of nicotine,however, may have some advantages over cocaine. For example, there issome level of standardization with nicotine delivery; that is, eachcigarette contains on average 9 mg of nicotine of which 1-3 mg areeffectively dispensed during smoking. Additionally, the peak plasmaconcentration of nicotine is 25-50 ng/ml which is significantly lowerthan that of cocaine (0.3-1 μg/ml). This should provide an idealOpportunity for intervention with moderately high affinity antibodies.

Initial vaccination with the therapeutic hapten-carrier conjugatecomposition of the present invention creates high titers ofhapten-specific antibodies in vivo. Periodic tests of the vaccinatedsubjects plasma are useful to determine individual effective doses.Titer levels are is increased and maintained through periodic boosting.It is anticipated that this therapeutic will be used in combination withcurrent drug rehabilitation programs, including counseling. Further, thetherapeutic compositions of the present invention may be aimed at asingle drug or n several drugs simultaneously or in succession and maybe used in combination with other therapies. For example, thetherapeutic hapten-carrier conjugate compositions and methods of theinstant invention are used without adverse interactions in combinationwith conventional n pharmacological approaches and previously discussed“short term” passive immunization to enhance the overall effect oftherapy.

The therapeutic hapten-carrier conjugate composition of n the presentinvention is prepared by coupling one or more hapten molecules to a Tcell epitope containing carrier to obtain a hapten-carrier conjugatecapable of stimulating T cells (immunogenic) which leads to T cellproliferation and a characteristic release of mediators which activaterelevant B cells and stimulate specific antibody production. Antibodiesof interest are those specific to the hapten portion of thehapten-carrier conjugate (also called the hapten-carrier complex).Therapeutic compositions containing a combination of conjugates, eitherto the same drug (cross-immunization) or to multiple drugs(co-immunization) are disclosed. Such co-mixtures of conjugates ofmultiple drugs are particularly useful in the treatment of polydrugabuse.

In selecting drug suitable for conjugation according to the instantinvention, one skilled in the art would select drug with propertieslikely to elicit high antibody titers. However, if the chosen moleculeis similar to those molecules which are endogenous to the individual,antibodies raised against such a molecule could cross-react with many isdifferent molecules in the body giving an undesired effect. Thus, thedrug to be selected as the hapten (drug/hapten) must be sufficientlyforeign and of a sufficient size so as to avoid eliciting antibodies tomolecules commonly found inside a human body. For these reasons,alcohol, for example, would not be suitable for the therapeutic of theinstant invention. The antibodies raised against the therapeuticcomposition are highly specific and of a sufficient quantity toneutralize the drug either in the blood stream or in the mucosa or both.Without limiting the invention, the drugs which are suitable fortherapeutic composition (not in order of importance) are:

-   Hallucinogens, for example mescaline and LSD;-   Cannabinoids, for example THC;-   Stimulants, for example amphetamines, cocaine, phenmetrazine,    methylphenidate;-   Nicotine;-   Depressants, for example, nonbarbiturates (e.g. bromides, chloral    hydrate etc.), methaqualone, barbiturates,-   diazepam, flurazepam, phencyclidine, and fluoxetine;-   Opium and its derivatives, for example, heroin, methadone, morphine,    meperidine, codeine, pentazocine, and-   propoxyphene; and-   “Designer drugs” such as “ecstasy”.

FIG. 6 shows the structure of four drugs suitable for conjugationaccording to the instant invention.

The carrier of the instant invention is a molecule containing at leastone T cell epitope which is capable of stimulating the T cells of thesubject, which in turn help the B cells initiate and maintain sustainedantibody production to portions of the entire conjugate, including thehapten portion. Thus, since a carrier is selected because it isimmunogenic, a strong immune response to the vaccine in a diversepatient population is expected. The carrier, like the hapten, must besufficiently foreign to elicit a strong immune response to the vaccine.A conservative, but not essential, approach is to use a carrier to whichmost patients have not been exposed to avoid the phenomenon ofcarrier-induced epitope suppression. However, even if carrier-inducedepitope suppression does occur, it is manageable as it has been overcomeby dose changes (DiJohn et al. (1989) Lancet 1415-1418) and otherprotocol changes (Etlinger et al. (1990) Science 249:423-425), includingthe use of CTB (Stok et al. (1994) Vaccine 12:521-526). Vaccines whichutilize carrier proteins to which patients are already immune arecommercially available. Still further, carriers containing a largenumber of lysines are particularly suitable for conjugation n accordingto the methods of the instant invention. Suitable carrier molecules arenumerous and include, but are not limited to:

Bacterial toxins or products, for example, cholera toxin B-(CTB),diphtheria

toxin, tetanus toxoid, and pertussis toxin and filamentoushemagglutinin, shiga toxin, pseudomonas exotoxin;

Lectins, for example, ricin-B subunit, abrin and sweet pea lectin;Sub virals, for example, retrovirus nucleoprotein (retro NP),

rabies ribonucleoprotein (rabies RNP), plant viruses (e.g. TMV, cow peaand cauliflower mosaic viruses), vesicular stomatitis virus-nucleocapsidprotein (VSV-N), poxvirus vectors and Semliki forest virus vectors;

Artificial vehicles, for example, multiantigenic peptides (MAP),microspheres;Yeast virus-like particles (VLPs);Malarial protein antigen;and others such as proteins and peptides as well as any modifications,derivatives or analogs of the above.

To determine features of suitable carriers, initial experiments wereperformed using bovine serum albumin as a protein carrier. The proteinhas been ideal for animal experiments, as it is inexpensive and containslarge numbers of lysines for conjugation. However, it is lessappropriate for human vaccination because the generation of anti-BSAantibodies has the potential to cause adverse responses. Thus, using theresults of these experiments, the above-described criteria were appliedto a large number of candidate carriers. The result is the list ofcarriers described above suitable for the practice of the instantinvention.

The carrier of a preferred embodiment is a protein or a branched peptide(e.g., multi-antigenic peptides (MAP)) or single chain peptide. An idealcarrier is a protein or peptide which is not commonly used invaccination in the country in which the therapy is used, therebyavoiding the potential of “carrier induced epitopic suppression.” Forexample, in the U.S., where standard childhood immunization includesdiphtheria and tetanus, proteins such as tetanus toxoid and diphtheriatoxoid, if unmodified, may be less desirable as appropriate carriers.Further, the carrier protein should not be a protein to which one istolerant. In humans, this would exclude unmodified human serum albumin.Further, many food proteins would have to be carefully screened beforeuse as a carrier. Again, in humans, bovine serum albumin would be lessdesirable as a carrier due to the beef in the diet of most humans. Stillfurther, it is highly advantageous if the carrier has inherentimmunogenicity/adjuvanticity. A delicate balance must be struck betweenthe desire for immunogenicity of the carrier and the desire to maximizethe anti-hapten antibody. Still further, the preferred carrier would becapable of both systemic response and response at the site of exposure.This is particularly true of cocaine and nicotine which are morefrequently administered across mucosal membranes. The speed of responseis especially critical where cocaine has been smoked. Accordingly, inthe case of cocaine and nicotine, a preferred carrier elicits not only asystemic response but also a pre-existing mucosal antibody response. Insuch a mucosal response the reaction of antibodies with cocaine and/ornicotine would happen rapidly enough to counteract the drug before itbegins circulating in the blood stream.

One such preferred carrier is cholera toxin B (CTB), a highlyimmunogenic protein subunit capable of stimulating strong systemic andmucosal antibody responses (Lycke (1992) J. Immunol. 150:4810-4821;Holmgren et al. (1994) Am. J. Trop. Med. Hyg. 50:42-54; Silbart et al.(1988) J. Immun. Meth. 109:103-112; Katz et al. (1993) Infection Immun.61:1964-1971). This combined IgA and IgG anti-hapten response is highlydesirable in blocking cocaine that is administered nasally or byinhalation, and in blocking nicotine that is absorbed in the mouth andlungs. In addition, CTB has already been shown to be safe for human usein clinical trials for cholera vaccines (Holmgren et al., supra;Jertborn et al. (1994) Vaccine 12:1078-1082; “The Jordan Report,Accelerated Development of Vaccines” 1993, NSAID, 1993).

Other useful carriers include those with the ability to enhance amucosal response, more particularly, LTB family of bacterial toxins,retrovirus nucleoprotein (retro NP), rabies ribonucleoprotein (rabiesRNP), vesicular stomatitis virus-nucleocapsid protein (VSV-N), andrecombinant pox virus subunits.

In yet another embodiment, various proteins derivatives, peptidesfragments or analogs, of allergens are used are carriers. These carriersare chosen because they elicit a T cell response capable of providinghelp for B cell initiation of anti-hapten antibodies. Examples of andmethods of making allergen proteins and peptides and their sequences aredisclosed in WO 95/27786 published Oct. 19, 1995. An allergen which isparticularly suitable as a carrier is Cryptomeria japonica, moreparticularly, recombinant Cry j 1, the sequence of which has beenpublished with slight variation. In countries other than Japan,Cryptomeria japonica is not prevalent. Therefore, Cry j 1 allergengenerally fits one of the criteria of a suitable carrier, that is acarrier to which a subject has not been previously exposed.

Using the methods and compositions of the present invention, and moreparticularly, the techniques set out in the Examples below, one skilledin the art links the selected drug/hapten with the selected carrier tomake the hapten-carrier conjugate of the instant invention.

In one embodiment of the present invention, the antibodies induced bythe therapeutic composition act within the time it takes for the drug totravel from the lungs through the heart to the brain. The ability toelicit this antibody response requires the careful selection of thecarrier molecule.

Production of Recombinant B Subunit of Cholera Toxin

Cholera toxin is the enterotoxin produced by Vibrio cholerae andconsists of five identical B subunits with each subunit having amolecular weight of 11.6 KDa (103 amino acids) and one A subunit of 27.2KDa (230 amino acids) (Finkelstein (1988) Immunochem. Mol. Gen. Anal.Bac. Path. 85-102). The binding subunit, CTB, binds to ganglioside GM1on the cell surface (Sixma et al. (1991) Nature 351:371-375; Orlandi etal. (1993) J. Biol. Chem. 268:17038-17044). CTA is the enzymatic subunitwhich enters the cell and catalyzes ADP-ribosylation of a G protein,constitutively activating adenylate cyclase (Finkelstein (1988)Immunochem. Mol. Gen. Anal. Bac. Path. pp. 85-102). In the absence ofthe A is subunit, cholera toxin is not toxic.

Others have disclosed the production of high level recombinantexpression of CTB pentamers (L'hoir et al. (1990) Gene 89:47-52; Slos etal. (1994) Protein Exp. Purif. 5:518-526). While native CTB iscommercially available, it is difficult to rule out contamination withCTA. Therefore, recombinant CTB has been expressed in E. coli and assayshave been developed for its characterization. The choleragenoidconstruct was purchased from the American Type Culture Collection(pursuant to U.S. Pat. No. 4,666,837). Recombinant CTB was cloned fromthe original vector (pRIT10810) into an expression plasmid (pET11d,Novagen) with an extra N-terminal sequence containing a His6 tag andexpressed in E. coli to the level of 25 mg/liter of culture. The proteinwas purified over a Ni column using standard techniques and analyzed onSDS-PAGE (see FIGS. 12 a, b and c). The recombinant CTB is monomeric inthis assay and is larger than the native CTB monomer due to theN-terminal extension.

Pentameric recombinant CTB was produced both with and without the Histag using the cDNA modified by PCR to include the Pel b leader sequence.A C-terminal Stop codon was inserted to remove the His tag. Bothconstructs were expressed in E. coli from the pET22b vector (Novagen).The His tagged protein was purified by Ni²⁺ affinity chromatography asabove (13 mg/L). The untagged recombinant CTB was purified byganglioside GM1 column affinity chromatography as described (Tayot etal. (1981) Eur. J. Biochem. 113:249-258). Recombinant CTB pentamer wasshown to bind to ganglioside GM1 in an ELISA and reacted withpentamer-specific antibodies in Western blots and ELISA. Recombinant CTBis also available from other sources, such as SBL Vaccin AB.

The pentameric structure of CTB may be preferred for binding toganglioside GM1. The pentamer is stable to SDS as long as the samplesare not boiled, permitting pentamerization to be assessed by SDS-PAGE.The gel in FIG. 12 a demonstrates that the native CTB is a pentamer nand is readily distinguishable from the denatured monomeric CTB.Pentamer structure is maintained over a pH range from 4 to 9 (see FIG.12 b), which facilitates a variety of conjugation chemistries. Therecombinant CTB initially expressed is monomeric. One way to obtainpentameric CTB is by making adjustments to express properly foldedpentameric CTB. It has been found that cytoplasmic expression provides amuch higher level of monomeric CTB. One skilled in the art is aware ofmethods of folding monomeric CTB into pentameric CTB (see, e.g., L'hoiret al. (1990) Gene 89:47-52). An alternative to re-folding monomeric CTBto obtain pentameric CTB is periplasmic expression which resulted inpentameric recombinant CTB able to bind GM1-ganglioside by ELISA. FIG.13 a and FIG. 13 b show the data supporting this finding. One skilled inthe art may find several approaches for obtaining gantameric recombinantCTB have been described, including periplasmic expression with a leader(Slos et al., supra; Sandez et al. (1989) Proc. Nat'l. Acad. Sci.86:481-485; Lebens et al. (1993) BioTechnol. 11:1574-1578) orpost-translational refolding (L'hoir et al., supra; Jobling et al.(1991) Mol. Microbiol. 5:1755-1767).

Another useful carrier is cholera toxin which provides improved mucosalresponse over CTB. It has been reported that the enzymatically active Asubunit adjuvant enhances activity (Liang et al. (1988) J. Immunol.141:1495-1501; Wilson et al. (1993) Vaccine 11:113-118; Snider et al.(1994) J. Immunol. 153:647).

One aspect of achieving the conjugate of the instant is inventioninvolves modifying the hapten, sufficiently to render it capable ofbeing conjugated or joined to a carrier while maintaining enough of thestructure so that it is recognized as free state hapten (for example, asfree cocaine or nicotine). It is essential that a vaccinated individualhas antibodies which recognize free hapten (cocaine or nicotine).Radioimmunoassay and competition ELISA assay (FIGS. 10 a and 10 b)experiments, explained in more detail in the Examples, can measureantibody titers to free hapten. Antibodies of interest arehapten-specific antibodies and, in some embodiments, arecocaine-specific antibodies or nicotine-specific antibodies. It shouldbe recognized that principles and methods used to describe the preferredembodiments may be extended from this disclosure to a wide range ofhapten-carrier conjugates useful in the treatment of a variety of drugaddictions and toxic responses.

Conjugates

Preparation of the Novel Cocaine-Carrier Conjugates of the instantinvention are derived from cocaine and cocaine metabolites, primarilyderivatives of norcocaine, benzoyl ecgonine and ecgonine methyl ester.As used herein, the term “cocaine-carrier conjugate” encompasses aconjugate comprised of a carrier linked to a cocaine molecule, amodified cocaine molecule, or any metabolite of cocaine. FIG. 4 shows arepresentation of the cocaine molecule as compared to these molecules.In the case of norcocaine and ecgonine methyl ester, the secondary amineand the secondary alcohol functional groups present in the two compoundsrespectively, are modified to provide a chemical linkage which enablesattachment to a protein carrier. In the case of benzoyl ecgonine, thefree acid is either used directly to attach to a carrier protein or ismodified with a linkage to facilitate the same. Preparation of the novelnicotine-carrier conjugates of the present invention are derived fromnicotine and nicotine metabolites. FIG. 19 shows a representation ofnicotine and some of its metabolites.

The length and nature of the hapten-carrier linkage is such that thehapten is displaced a sufficient distance from the carrier domain toallow its optimal recognition by the antibodies initially raised againstit. The length of the linker is optimized by varying the number of —CH₂—groups which are strategically placed within a “branch” selected fromthe group consisting of:

-   -   CJ 0 Q    -   CJ 1 (CH₂)_(n)Q    -   CJ 1.1 CO₂Q    -   CJ 1.2 COQ    -   CJ 2 OCO(CH₂)_(n)Q    -   CJ 2.1 OCOCH=Q    -   CJ 2.2 OCOCH(O)CH₂    -   CJ 2.3 OCO(CH₂)_(n)CH(O)CH₂    -   CJ 3 CO(CH₂)_(n)COQ    -   CJ 3.1 CO(CH₂)_(n)CNQ    -   CJ 4 OCO(CH₂)_(n)COQ    -   CJ 4.1 OCO(CH₂)_(n)CNQ    -   CJ 5 CH₂OCO(CH₂)_(n)COQ    -   CJ 5.1 CH₂OCO(CH₂)_(n)CNQ    -   CJ 6 CONH(CH₂)_(n)Q    -   CJ 7 Y(CH₂)_(n)Q    -   CJ 7.1 CH₂Y(CH₂)_(n)Q    -   CJ 8 OCOCH(OH)CH₂Q    -   CJ 8.1 OCO(CH₂)_(n)CH(OH)CH₂Q    -   CJ 9 OCOC₆H₅    -   CJ 10 shown on FIG. 2 b    -   CJ 11 YCO(CH₂)_(n)COQ        and shown in FIGS. 2 a and 2 b herein. With regard to the above        branches, n is an integer preferably selected from about 3 to        about 20, more particularly about 3 to about 6; Y is preferably        is selected from the group consisting of S, O, and NH; and Q is        preferably selected from the group consisting of:

-   (1) —H

-   (2) —OH

-   (3) —CH₂

-   (4) —CH₃

-   (4a) —OCH₃

-   (5) —COOH

-   (6) halogen

-   (7) protein or peptide carrier

-   (8) modified protein or peptide carrier

-   (9) activated esters, such as 2-nitro-4-sulfophenyl ester and    N-oxysuccinimidyl ester

-   (10) groups reactive towards carriers or modified carriers such as    mixed anhydrides, acyl halides, acyl azides, alkyl halides,    N-maleimides, imino esters, isocyanate, isothiocyanate; or

-   (11) another “branch” identified by its “CJ” reference number.

A T cell epitope containing carrier (e.g., a protein or peptide carrier)may be modified by methods known to those skilled in the art tofacilitate conjugation to the hapten (e.g., by thiolation). For examplewith 2-iminothiolane (Traut's reagent) or by succinylation, etc. Forsimplicity, (CH₂)_(n)Q, where Q=H, may be referred to as (CH₃), methylor Me, however, it is understood that it fits into the motif asidentified in the “branches” as shown in FIGS. 2 a and 2 b.

Further abbreviations of commercially obtainable compounds used hereininclude:

BSA=Bovine serum albumin

DCC=Dicyclohexylcarbodiimide DMF=N,N-Dimethylformamide

EDC (or EDAC)=N-Ethyl-N′-(3-(dimethylamino) propyl) carbodiimidehydrochlorideEDTA=Ethylenediamine tetraacetic acid, disodium saltHATU=O-(7-Azabenzotriazol-1-yl)-1,1,3,3-tetramethyluroniumhexafluorophosphate

NMM=N-Methylmorpholine

HETU=2-(1H-Benzotriazole-1-yl)-1,1,3,3-tetramethyluroniumhexafluorophosphateTNTU=2-(5-Norbornene-2,3-dicarboximido)-1,1,3,3-tetramethyluroniumtetrafluoroboratePyBro®=Bromo-tris-pyrrolidino-phosphonium hexafluorophosphate

HOBt=N-Hydroxybenzotriazole

Further the IUPAC nomenclature for several named compounds are:

Norcocaine:

-   3β-(Benzoyloxy)-8-azabicyclo[3.2.1]octane-2β-carboxylic acid methyl    ester

Benzoyl Ecgonine:

-   3β-(Benzoyloxy)-8-methyl-8-azabicyclo[3.2.1]octane-2β-carboxylic    acid

Cocaine:

-   3β-(Benzoyloxy)-8-methyl-8-azabicyclo[3.2.1]octane-2β-carboxylic    acid methyl ester

Ecgonine Methyl Ester:

-   3β-(Hydroxy)-8-methyl-8-azabicyclo[3.2.1]octane-2β-carboxylic acid    methyl ester

Nicotine

-   1-Methyl-2-(3-pyridyl)pyrrolidine

Cotinine

-   N-Methyl-2-(3-pyridyl)-5-pyrrolidone

Reactions

In one embodiment, precursors of the conjugates of the instant inventionare synthesized by acylating ecgonine methyl ester with bromoacetylbromide in DMF in the presence of two equivalents ofdiisopropylethylamine. The product is then coupled to the thiol group ofa thiolated carrier protein to obtain a conjugate with the generalstructure of PS-2 (see FIG. 3 a and Example 1).

In another embodiment, precursors of the conjugates of the instantinvention are synthesized by succinylating ecgonine methyl ester withsuccinic anhydride in DMF in the presence of one equivalent oftriethylamine. The product is then coupled to the amino group of alysine residue of a carrier protein to obtain a conjugate with thegeneral structure of PS-4 (see FIG. 3 a and Example 2).

In yet another embodiment, precursors of the conjugates of the instantinvention are synthesized by reacting norcocaine with succinic anhydridein methylene chloride in the presence of two equivalents oftriethylamine. Alternatively, precursors of the conjugates of theinstant invention are synthesized by reacting a solution of norcocainemonoactivated succinic acid and triethylamine to form succinylatednorcocaine. In either case, the resulting succinyl norocaine consists ofa mixture of at least two isomers, namely the exo and endo forms of thesuccinyl group (see FIG. 20). We have demonstrated using ¹H-NMR analysisthat the ratio of exo:endo is dependent upon the dielectric constant (E)of the solvent used (see FIG. 21). The lower the dielectric constant,the higher the ratio of one isomer. The is mixture is the result of adynamic equilibrium process and the isomers are not readily separable.

Succinyl norocaine can then be coupled to the E-amino group of a lysineresidue of a carrier protein using EDC to obtain a conjugate with thegeneral structure of PS-5 (see FIG. 3 a and Method A of Example 3).Conjugates with the general structure of PS-5 may be obtained in analternative set of reactions. In this alternative, the proteinconjugation can be carried out using a pre-activated succinylatednorcocaine derivative. That is, the intermediate can be isolated andcharacterized. The pre-activated succinylated norcocaine derivative issynthesized by reacting 4-hydroxy-3-nitrobenzene sulfonic acid sodiumsalt with succinylated norcocaine in the presence ofdicyclohexylcarbodiimide (DCC) and DMF. The product is conjugated to theamino group of a lysine residue of a carrier protein to obtain aconjugate with the general structure of PS-5 (See FIG. 3 a and Example7, Method B)

In still another embodiment, compounds of the instant invention aresynthesized by reacting succinylated norcocaine with N-hydroxysuccimidein the presence of ethyl chloroformate, N-methylmorpholine (NMM) andDMF. The product is then coupled to the amino group of a lysine residueof a carrier protein to obtain a conjugate with the general structure ofPS-5 (see FIG. 3 a and Example 7, Method C).

In another embodiment, compounds of the instant invention aresynthesized by reacting thionyl chloride with succinylated norcocaine.The product is then conjugated to a carrier protein to obtain aconjugate with the general structure of PS-5 (see FIG. 3 a and Example7, Method A).

In another embodiment, compounds of the instant invention aresynthesized by reacting succinylated norcocaine with HATU in DMF anddiisopropylethylamine (Carpino (1993) J. Am. Chem. Soc. 115:4397-4398).The product was added to an aqueous solution containing the carrierprotein to obtain a conjugate with the general structure PS-5 (see FIG.3 a and Method A of Example 7).

In another embodiment, compounds of the instant invention aresynthesized by reacting succinylated norcocaine with HBTU in DMF anddiisopropylethylamine. The product was added to an aqueous solutioncontaining the carrier protein to obtain a conjugate with the generalstructure PS-5 (see FIG. 3 a and Method B of Example 7).

In yet another embodiment, compounds of the instant invention aresynthesized by reacting succinylated norcocaine with TNTU in DMF anddiisopropylethylamine. The product was added to an aqueous solutioncontaining the carrier protein to obtain a conjugate with the generalstructure PS-5 (see FIG. 3 a and Method C and D of Example 7).

In still another embodiment, compounds of the instant invention aresynthesized by reacting succinylated norcocaine with PyBroP in DMF anddiisopropylethylamine. The product was added to an aqueous solutioncontaining the carrier protein to obtain a conjugate with the generalstructure PS-5 (see FIG. 3 a and Method E and F of Example 7).

Alternatively, compounds of the instant invention are synthesized bysuccinylating the carrier protein with succinic anhydride in boratebuffer. The product is then coupled to noncocaine in the presence of EDCto obtain a conjugate with the general structure of PS-5 (see FIG. 3 aand Method B of Example 3).

In another embodiment, compounds of the instant invention aresynthesized by reducing the free acid in benzoyl ecgonine to itscorresponding primary alcohol, using borane-dimethylsulfide complex. Thealcohol is reacted with succinic anhydride in DMF, is the product ofwhich is then conjugated to the free amino acid group of a carrierprotein in the presence of EDC to obtain a conjugate with the generalstructure of PS-6 (see FIG. 3 a and Example 4).

In another embodiment, compounds of the instant invention aresynthesized by conjugating benzoyl ecgonine to the amino group of alysine residue of a carrier protein in the presence of EDC to obtain aconjugate with the general structure of PS-9 (see FIG. 3 a and Example5).

The PS-5 analogs of CTB are synthesized using the protocols described inExample 6. The various methods described in Example 6 for synthesizingPS-5 analogs of CTB yield PS-5 analogs with different degrees ofhaptenation. The degree of haptenation can be determined by UVabsorption or time of flight (TOF) mass spectral analysis. Table 2 showsthat haptenation was achieved using several conjugates (some with CTB asa carrier) made pursuant to the methods of the instant invention.Different batches are indicated by adding a decimal and a numberthereafter, e.g., PS-5 batch 6 is PS-5.6. The hapten-carrier conjugatesof the invention can be haptenated to different degrees by using themethods described in Example 6 as well as various methods of conjugationknown to those skilled in the art, e.g., different choices of activatingagents, different buffers, different reaction times, etc. The amount ofhaptenation of the conjugate is limited, however, by the number ofnucleophilic groups contained within the carrier.

In one embodiment, the precursor of the conjugates PS-54 weresynthesized by acylating racemic nornicotine with succinic anhydride inmethylene chloride in the presence of two equivalents ofdiisopropylethylamine. The product of this reaction is then coupled tothe lysine residue of a carrier protein using HATU to obtain theconjugates PS-54 (see Example 26, method B).

In another embodiment, the precursors of PS-55, PS-56, PS-57 and PS-58were synthesized by selectively alkylating the pyridine nitrogen in(S)-(−)-nicotine in anhydrous methanol, with ethyl 3-bromobutyrate,5-bromovaleric acid, 6-bromohexanoic acid or 8-bromooctanoic acidrespectively (see Example 27, methods A, B, C, and D). The products ofthese reactions were conjugated to a carrier protein using HATU toobtain the conjugates PS-55, PS-56, PS-57 and PS-58 (see Example 28,Method A).

TABLE 2 Carrier Haptens/ Conjugation Conjugate Protein Monomer MethodPS-2.2 BSA 16 Ex 1 PS-4.3 BSA 24 Ex 4 PS-5.1 BSA  4-20 Ex 3, Method APS-5.4 BSA 29 Ex 3, Method A PS-5.6 BSA 20 Ex 3, Method A PS-5.7 BSA 27Ex 3, Method B PS-6.1 BSA 9 Ex 4 PS-9 BSA 1-2 Ex 5 PS-9.2 BSA 7 Ex 5PS-5.6 CTB 1.25 Ex 6, Method A PS-5.7 CTB <1 Ex 7, Method A PS-5.8 CTB1.9 Ex 6, Method A PS-5.9 CTB 0.9-6.5 Ex 7, Method B PS-5.10 CTB 0.5-2.5Ex 7, Method C PS-11 CTB 1.0-7.8 Ex 6, Method A PS-5.53 CTB 3.4 Ex 6,Method A PS-5.70 CTB NA Ex 6, Method B PS-5.168 rCTB  5.7-11.8 Ex. 6,Method L PS-5.174 rCTB 6.9-10  Ex. 6, Method L PS-5.179 rCTB  5.8-11.8Ex. 6, Method L PS-5.169 rCTB 5.3-7.7 Ex. 6, Method G PS-5.175 rCTB4.0-7.7 Ex. 6, Method G PS-5.180 rCTB  6.6-10.7 Ex. 6, Method G PS-5.185rCTB 7.3-12  Ex. 6, Method G PS-5.170 rCTB 2.7-7.8 Ex. 6, Method MPS-5.176 rCTB 1.0-5.6 Ex. 6, Method M PS-5.181 rCTB 1.7-5.4 Ex. 6,Method M PS-5.184 rCTB 1 Ex. 6, Method M PS-5.171 rCTB 1.0-6.9 Ex. 6,Method H PS-5.177 rCTB 0.9-4.5 Ex. 6, Method H PS-5.182 rCTB  3.2-607Ex. 6, Method H PS-5.186 rCTB 3.8-6.5 Ex. 6, Method H PS-5.187 rCTB1.6-6.5 Ex. 6, Method I PS-5.189 rCTB 1 Ex. 6, Method I PS-5.194 rCTB0.3-2.8 Ex. 6, Method I PS-5.195 rCTB 0.9-3.0 Ex. 6, Method I PS-5.196rCTB 0.6 Ex. 6. Method I PS-5.200 rCTB 1.0-5.5 Ex. 6, Method I PS-54 BSA19.5 Example 26, Method B PS-54 HEL 3.2 Example 26, Method B PS-55 BSA33.2 Example 28, Method A PS-55 HEL 1.09 Example 28, Method A PS-56 BSA27 Example 28, Method A PS-56 HEL 2.2 Example 28, Method A PS-57 BSA 81Example 28, Method A PS-57 HEL 8 Example 28. Method A PS-58 BSA 66.8Example 28, Method A PS-58 HEL 7.4 Example 28, Method A NA—not available

This is a non-limiting list of conjugates. Other conjugates have beenmade with greater than one hapten coupled to the T cellepitope-containing carrier. Preferably, 1 to 100 haptens are coupled tothe T cell epitope-containing carrier. Most preferably, 1 to 70 haptensare coupled to the T cell epitope containing carrier.

Methods of synthesizing compounds PS-2, PS-3, PS-4, PS-b, PS-6, PS-9,PS-54, PS-55, PS-56, PS-57 and PS-58 are disclosed in the Examples.Following the methods disclosed, e.g., using activating agents underaqueous conditions, one skilled in the art can synthesize compoundsPS-10 to PS-53 (see FIGS. 3 b(1) and (2)).

Hydrolysis of the methyl ester in the PS-2, PS-4, and PS-5 conjugatesleads to the production of benzoyl ecgonine-specific antibodies, thusrendering the conjugate essentially ineffective as a therapeuticvaccine. For optimal conjugation and to prevent extensive hydrolysis ofthe methyl ester in the succinylated norcocaine and PS-5 conjugates, thebuffer pH during conjugation is carefully controlled. Landry, AmericanChemical Society, Division of Medicinal Chemistry, 212th ACS NationalMeeting, Abstract No. 161 (1996), indicates that the stability of themethyl ester in cocaine is lower than the 23 corresponding ester inpseudococaine and in N-acylated norcocaine, when studied under the sameconditions. Since succinylated norcocaine is an N-acylated derivative ofnorcocaine, the stability of the methyl ester was investigated underbasic conditions. HPLC analysis of succinylated norcocaine at pH 6, 7and 8 at 5° C. indicates that hydrolysis is essentially undetectableover 24 hours. The time for 5% degradation at 25° C. at the same pHvalues decreases from 1.30 years at pH 6 to 10.96 days at pH 8. Thus,the degradation follows first order kinetics and shows a strong pHdependency. At higher pH ranges (e.g., pH 9 and 10) the rate ofhydrolysis is faster.

This marked increase in stability over cocaine may be thought of asbeing due to the inability of the tropane nitrogen to stabilize thehydrolysis intermediate (see FIG. 22). Our preferred conditions forformulating the conjugate are based upon its solubility and stability,along with the need to produce a sterile finished product. Thispreferred formulation is amenable to sterilization by filtration. Theeffect of pH on the solubility of the conjugate at 25″C was tested. Theconjugate was quantitated using total nitrogen analysis. The equilibriumsolubility of the conjugate is near 200 μg/ml at all pH values below8.0. However, below pH 8, a very significant amount of the totalconjugate (approximately 80%) is lost as a result of filtersterilization. To completely solubilize the is conjugate for passagethrough a sterile filter, a pH value of at least 10 is preferred.Accordingly, preferred conditions for the filter sterilization processare filtration at pH 10.0 and 5° C. for one hour or less. Preferably,such filtration is followed by adsorption of the conjugate onto sterileAlum to n drop the formulation pH to physiologic values. The sterileconjugate-Alum suspension preferably is then filled into vials andstored at 5° C. Other buffers may be utilized to promote solubilitybelow pH 10.

Methods to monitor the stability of the methyl ester can be bothimmunological and physiochemical. A cocaine-specific monoclonal antibodyhas been generated which can discriminate between cocaine and itsmetabolites when attached to the protein carrier. The reactivity toinactive metabolites was 2000 times n less than to cocaine.Benzoylecgonine-specific monoclonal antibodies can be generated in-houseusing similar technology. Either monoclonal antibody or preferably bothcan be used to measure levels of intact and hydrolyzed conjugatescompared to standard mixtures. This differentiation depends on therelative reactivity of each monoclonal antibody to the hydrolyzed andintact conjugate. In another embodiment a carbon-13 enriched containingmethyl ester analog of succinylated norcocaine can be synthesized (FIG.16). When conjugated to a carrier protein to form PS-5, carbon-13nuclear magnetic resonance spectroscopy (¹³C NMR) can be used to monitorthe presence of the methyl ester and since the methyl group is isotopeenriched, the signal corresponding to the methyl ester will bedistinguishable above the protein signals.

In another embodiment a radioactively labelled methyl ester containingconjugate can be synthesized. This could include either a carbon-14 ortritium containing methyl ester analog of succinylated norcocaine. Whenconjugated to a carrier protein to form PS-5, the loss of radioactivityfrom either analog over time can be monitored using techniques known tothose familiar with the art. Monitoring the loss of radioactivity willthen indicate the residual levels of intact methyl ester.

The benzoate ester group in the PS-5 conjugates is essentially stableunder the conditions of conjugation and purification, and thereforerequires no monitoring for retention of structural integrity. If,however, increased bioavailability is desirable then incorporation of anamide bond or some other metabolically stable group, known to thosefamiliar with the art, can be incorporated into the conjugate.Similarly, the methyl ester in the PS-5 conjugates can be stabilizedusing the branch CJ6 where Q=H, i.e. an amide bond. This incorporationwould-increase both the in vitro and in vivo stability of theconjugates.

HPLC Analysis of CTB Cocaine Conjugates

Reverse phase HPLC is used as an in-process control to monitor theconjugation of succinylated norcocaine to recombinant cholera toxin Bsubunit (rCTB). This method shows how levels of haptenation change withrespect to reaction time and differential levels of activating agent. Inaddition, byproducts of the reaction and residual small organiccompounds, e.g unreacted succinylated norcocaine, can be measured. Alsothe amount of unreacted rCTB may be quantitated with respect to theproduct. A reverse phase column was chosen in order that components ofthe product may be separated with respect to number of haptens per rCTBmonomer as the product becomes increasingly hydrophobic with theaddition of each succinylated norcocaine molecule.

Conjugate CTB-5.200 was analyzed by RP HPLC (as described in Example 30,Method A) to measure the retention time of the conjugate, the percentageof unconjugated rCTB, and the amount of residual unreacted succinylatednorcocaine. This assay was performed five times on CTB-5.200 todemonstrate reproducibility of the instrument and the process. Usingthis process unreacted rCTB eluted at 24.1 minutes with an unresolvedshoulder at 25.6 minutes. This could be accounted for by theheterogeneity of the rCTB amino terminus. The amount of unreacted rCTBin the conjugate was consistently less than 1% as measured at 210 nm.Conjugated material eluted as a broad multiplet of peaks beginning at25.6 minutes and continuing to 37 minutes (data not shown). The amountof residual succinylated norcocaine was negligible (<0.1%).

The conjugate CTB5-200 was separated into various fractions using asemi-preparative method (see Example 30, Method B). Lyophilizedfractions were resuspended in 20% acetonitrile 0.1% TFA and analyzed bymass spectrometer and analytical RP HPLC (as so previously described inExample 30, Method A). The mass spectral analysis indicated that theconjugate had been fractionated by level of haptenation with later peaksshowing higher levels of haptenation. Analytical RP HPLC revealedseveral peaks within each fraction, this was expected as baselineresolution was not achieved at the semi-preparative scale. Thereappeared to be a trend whereby the more highly haptenated species had alonger retention time as compared to unconjugated material or evenmaterial containing only one hapten (data not shown). The first fractioncollected at 24.1 minutes was found to be completely unreacted materialwhereas fraction four at 28.8 minutes was had 3.5 haptens/monomer.Moreover, fraction number eight, with an elution time of 39 minutescontained the most highly haptenated molecules (7.6 haptens/monomer).Chromatographic separation of the constitutive components of theconjugate appeared to be based on level of haptenation; although thereremains the possibility that differentially haptenated residues may leadto variation in hydrophobicity and thus level of haptenation would notbe the only basis for separation.

In yet another embodiment, compounds PS-27 to PS-50 are synthesized viaa series of reaction which allow a novel entry into the tropane class ofalkaloids. This novel route involves a free radical mediated 1,6diene-like intermolecular cyclization (March, Advanced OrganicChemistry: Reactions, Mechanisms and Structure, (1992) 4th ed.,Wiley-Interscience, p. 744, and references cited therein). Tropanealkaloids, in particular cocaine and its analogs, have been previouslysynthesized; however these routes involve multiple steps and usuallyresolution of an intermediate (Wilstatter et al. (1923) Ann. Chem.434:111-139; Tufariello et al. (1979) J. Am. Chem. 101:2435-2442; Lewinet al. (1987) J. Heterocyclic Chem. 24:19-21; and Simoni et al. (1993)J. Med. Chem. 36:3975-3977). Although limited to the synthesis of3-aryltropane derivatives, Davies et al. (U.S. Pat. No. 5,262,428),synthesized cocaine analogs by decomposing vinyldiazothanes in thepresence of pyrroles to form a tropane ring which is then followed by aGrignard addition to provide the cocaine analogs. In this alternativeembodiment, novel cocaine-carrier conjugates with “remote site” branchesare synthesized. As used herein “remote sites” are labelled C, D and Eon FIG. 1. Those sites pose special challenges to the chemist due to thenature of the tropane ring and are especially difficult positions for“branches” necessary for conjugates of the instant invention. Oneembodiment, adds the “branches” then builds the tropane ring last. Asrepresented in FIG. 15, there is a novel single step addition of theradical 2 and cyclization of, at low temperature, general compound 1.The stereochemical outcome is defined by the boat-like form of theintermediate 3 in which addition of the radical 2 occurs equatorially atposition 3 followed by ring closure by the predicted mechanism, whichgives the 3-benzoate ester adduct 4 (cocaine analog). The orientation ofC, D, E and CO₂R would be predefined in 1.

There is a wide range of compounds which have been developed tofacilitate cross-linking of proteins/peptides on conjugation is ofproteins to derivatized molecules, e.g., haptens. These include, but arenot limited, to carboxylic acid derived active esters (activatedcompounds), mixed anhydrides, acyl halides, acyl azides, alkyl halides,N-maleimides, imino esters, isocyanates and isothiocyanates, which areknown to those skilled in the art. These are capable of forming acovalent bond with a reactive group of a protein molecule. Dependingupon the activating group, the reactive group is the amino group of alysine residue on a protein molecule or a thiol group in a carrierprotein or a modified carrier protein molecule is which, when reacted,result in amide, amine, thioether, amidine urea or thiourea bondformation. One skilled in the art may identify further suitableactivating groups, for example, in general reference texts such asChemistry of Protein Conjugation and Cross-Linking (Wong (1991) CRCPress, Inc., Boca Raton, Fla.). Ideally, conjugation is via a lysineside chain amino group. Most reagents react preferentially with lysine.An especially suitable carrier is CTB as it has 9 lysine residues permonomer in its native form. To determine if conjugated pentameric CTBretains its structure and activity, GM1 ganglioside binding can beassessed.

Applicants have expressed and purified amounts of recombinant CTB which,once optimized, are produced in large fermentation batches. Processesfor expressing and purifying recombinant protein are know in the art,for example, U.S. Ser. No. 07/807,529. For example, CTB may be purifiedby affinity chromatography (Tayot et al. (1981) Eur. J. Biochem.113:249-258), conjugated to cocaine or nicotine derivatives, and theconjugate may then be further purified. The purified CTB and theresulting conjugate are analyzed for purity and for maintenance of thepentameric structure of CTB. Techniques include SDS-PAGE, native PAGE,gel filtration chromatography, Western blotting, direct and GM1-captureELISA, and competition ELISA with biotinylated CTB. Level of haptenationis measured by mass spectrometry, reverse phase HPLC and by analysis ofthe increase in UV absorbance resulting from the presence of the hapten.Both the solubility and the stability of the conjugate are optimized inpreparation for full-scale formulation. Details of some of theseanalyses are given in the Examples.

Although the pentameric structure of CTB is a preferred carrier forpractice of the present invention, and G_(M1) binding is an effectiveassay to determine that the pentameric form of CTB is present, thepresent invention is not limited to the use of the pentameric form ofCTB. Other T cell epitope carriers u are encompassed in the invention,as well as other forms of CTB (e.g., monomer, dimer, etc.) that may bemanipulated for use in the invention. If a carrier other than thepentameric form of CTB is utilized, then one skilled in the art woulduse an appropriate assay to determine the presence and activity of therequired carrier (e.g., the use of G_(M1) binding to determine thepresence of the pentameric form of CTB).

Several conjugates produced according to the present invention includeconjugates with analogs of cocaine and either BSA, HEL or CTB as theprotein carrier. Six representative cocaine analogs are shown in FIG. 3a. Of the six, PS-2, PS-4, PS-5, PS-6, and PS-9 were conjugated with BSAor HEL, while PS-5 was also conjugated with CTB. (See Table 2 above). Inaddition, several conjugates according to the present invention includeconjugates with analogs of nicotine.

In order to vary levels of haptenation, alternative approaches aretaken. In one embodiment the carrier is haptenated with a multivalentcocaine or nicotine construct. This idea is based on the concept ofmultiple antigenic peptides w (MAP) (Lu et al. Mol. Immunol., 28:623-630(1991)). In this system, multiple branched lysine residues are exploitedto maximize hapten density and valency. The premise of this approach isthat the immune response is enhanced if there are multiple copies of thehapten attached to the same peptide or is protein molecule. Therefore, amultivalent hapten which needs to be attached to only one or two siteson the carrier CTB pentamer is prepared as set out herein. The core ofsuch a multiple antigenic hapten is a branched polylysine core assuggested by Tam (Lu et al., supra). A chemically reactive n handle ispreserved by inclusion of a protected Cys residue. After cocaine ornicotine haptenation of all available amino groups, the sulfhydryl ofCys is unmasked and made available for coupling to the protein with anyof several bifunctional sulfhydryl/amino specific cross-linkers(Yoshitake et al. (1979) Eur. J. Biochem. 101:395-399. A number ofdendrimeric structures are used as a core.

Adjuvant

Any adjuvant which does not mask the effect of the carrier is considereduseful in the cocaine and nicotine therapeutic vaccines of the presentinvention (see, Edelman (1980) Rev. Infect. Dis. 2:370-373). Initialexperiments aimed at demonstrating the feasibility of a therapeuticvaccine against cocaine addiction used the powerful adjuvant CFA (FIGS.9 a and c). However, CFA is not preferred in humans. A useful adjuvantcurrently licensed for use in humans is alum, including aluminumhydroxide (Spectrum Chem. Mtg. Corp., New Brunswick, N.J.) or aluminumphosphate (Spectrum). Typically, the vaccine is adsorbed onto the alum,which has very limited solubility. Preliminary data in the murine modelsuggests that alum is capable of inducing a strong anti-cocaine antibodyresponse (FIG. 9 b), and MF59 (Chiron, Emeryville, Calif.) or RIBIadjuvant is also suitable.

Effective immunization with CTB as the carrier protein does not requirea powerful adjuvant. As shown in the Examples, high titer anti-cocaineantibody responses were induced by immunization with the CTB-cocaineconjugate either using alum as the adjuvant or in the absence of anyadded adjuvant. For carriers other than CTB one skilled in the art wouldbe capable of determining an appropriate adjuvant, if needed.

Excipients and Auxiliary Agents

Therapeutic compositions may optionally contain one or morepharmaceutically acceptable excipients including, but not limited to,sterile water, salt solutions such as saline, sodium phosphate, sodiumchloride, alcohol, gum arabic, vegetable oils, benzyl alcohols,polyethylene glycol, gelatine, mannitol, n carbohydrates, magnesiumstearate, viscous paraffin, fatty acid esters, hydroxy methyl cellulose,and buffer. Other suitable excipients may be used by those skilled inthat art. The therapeutic composition may optionally comprising at leastone auxiliary agent, for example, dispersion media, coatings, such aslipids and liposomes, surfactants such as wetting agents andemulsifiers, lubricants, preservatives such as antibacterial agents andanti fungal agents, stabilizers and other agents well known to thoseskilled in the art. The composition of the present invention may alsocontain further adjuvants, agents and/or inert pharmacologicallyacceptable excipients which may be added to enhance the therapeuticproperties of the drug or enable alternative modes of administration.

Highly purified hapten-carrier conjugates produced as discussed abovemay be formulated into therapeutic compositions of the inventionsuitable for human therapy. If a therapeutic composition of theinvention is to be administered by injection (i.e., subcutaneousinjection), then it is preferable that the highly purifiedhapten-carrier conjugate be soluble in aqueous solution at apharmaceutically acceptable pH (that is, a range of about 4-9) such thatthe composition is fluid and easy administration exists. It is possible,however, to administer a composition wherein the highly purifiedhapten-carrier conjugate is in suspension in aqueous solution and such asuspension is is within the scope of the present invention. Thecomposition also optionally includes pharmaceutically acceptableexcipients, adjuvant and auxiliary agents or supplementary activecompounds. Depending upon the mode of administration, optionalingredients would ensure desirable properties of the therapeutic ncomposition, for example, proper fluidity, prevention of action ofundesirable microorganisms, enhanced bioavailability or prolongedabsorption.

A therapeutic composition of the invention should be sterile, n stableunder conditions of manufacture, storage, distribution and use, andpreserved against the contaminating action of microorganisms such asbacteria and fungi. A preferred means for manufacturing a therapeuticcomposition of the invention in order to maintain the integrity of thecomposition is to prepare the formulation of conjugate andpharmaceutically excipient such that the composition may be in the formof a lyophilized powder which is reconstituted in excipients orauxiliary agents, for example sterile water, just prior to use. In thecase of sterile powders for the preparation of sterile injectablesolutions, the preferred methods of preparation are vacuum drying,freeze-drying or spin drying which yields a powder of the activeingredient plus any additional desired ingredient from a previouslysterile-filtered solution thereof.

The active compounds of this invention can be processed in accordancewith conventional methods of galenic pharmacy to produce therapeuticcompositions for administration to patients, e.g., mammals includinghumans. The preferred modes of administration are intranasal,intratracheal, oral, dermal, and/or injection. One particularly suitablecombination of modes of administration comprises an initial injectionwith intranasal boosts.

For parenteral application, particularly suitable are injectable,sterile solutions, preferably oily or aqueous is solutions, as well assuspensions, emulsions, or implants, including suppositories. Ampoulesare convenient unit dosages. For enteral application, particularlysuitable are tablets, dragees, liquids, suspensions, drops,suppositories, or capsules, which may include enteric coating. A syrup,elixir, or the like can be used wherein a sweetened vehicle is employed.

Sustained or directed release compositions can be formulated, e.g.,liposomes or those wherein the active compound (conjugate) is protectedwith differentially degradable coatings, e.g., by microencapsulation,multiple coatings, etc. It is also possible to freeze-dry the newcompounds and use the lyophilizates obtained, for example, for thepreparation of products for injection.

For topical application, there are employed as nonsprayable forms,viscous to semi-solid or solid forms comprising a carrier compatiblewith topical application and having a dynamic viscosity preferablygreater than water. Suitable formulations include but are not limited tosolutions, suspensions, emulsions, creams, ointments etc., which are, ifdesired, sterilized or mixed with auxiliary agent. For topicalapplication suitable are sprayable aerosol preparations wherein theactive compound, preferably in combination with a suitable excipient orauxiliary agent, is packaged in a squeeze bottle or in admixture with apressurized volatile, normally gaseous propellant.

An antibody raised through the compositions and methods of the instantinvention may have a molecular weight ranging from 150 KDa to 1,000 KDa.When the subject is exposed to free to cocaine or nicotine aftervaccination with the optimized conjugate in the therapeutic composition,the free cocaine or nicotine is targeted by cocaine-specific ornicotine-specific antibody or antibodies. No changes in the form orstructure of the drug are necessary for the antibody to recognize thedrug in is vivo. While not intending to limit the present invention, itis believed that upon exposure of the vaccinated individual to cocaineor nicotine, the anti-drug antibodies will block the effects of cocaineand nicotine. At least three mechanisms are believed to contribute tothe blocking activity. First, n antibodies are unable to cross theblood-brain barrier. Therefore, it is believed that cocaine or nicotine,when bound to the anti-cocaine or anti-nicotine antibody, will not crossthe blood-brain barrier and will not be able to exert its effect ondopamine transporters. Second, the antibody prevents the n drug frombinding to its receptor by simple steric blockade. This mechanism isexpected to be operative in blocking some of the non-CNS effects of thedrugs (e.g. cardiac toxicity) and in the activity of antibodies againstother drugs with non-CNS targets. Third, both cocaine and nicotine haverelatively short n half-lives in vivo due to both enzymatic andnon-enzymatic degradation, creating inactive metabolites. Cocaine andnicotine, in particular, are sufficiently small drugs so that it is veryunlikely that they could cross-link antibodies, thus, it is highlyunlikely that physiologically significant immune complex formation willoccur for either of the drugs.

Still further embodiments of mucosal applications are used in thepractice of the present invention. For example, copolymer microspheresare used to induce or enhance a mucosal immune response. These small,biodegradable microspheres encapsulate and protect the conjugate andfacilitate uptake by the mucosal immune system. Although they are mostwidely used for oral immunization, they also have been reported to beeffective with intranasal immunization (Walker (1994) Vaccine12:387-399). Inert polymers such as poly(lactide-co-glycolide) (PLG) of1-10 μm diameter are particularly useful in this regard (Holmgren et al.(1994) Am. J. Trop. Med. Hyg. 50:42-54; Serva (1994) Science265:1522-1524).

In addition to the preferred conjugates, cross-immunization is withdifferent conjugates is carried out in order to minimize antibodycross-reactivity. Mice are primed with conjugates, more particularlyPS-5 or PS-9 conjugates, and then boosted at day 14 with the reciprocalPS-9 or PS-5 conjugates coupled to the same carrier, BSA. Only thesubset of antibody-secreting B cells that recognize both of the cocaineconjugates are maximally stimulated and expanded. It is believed thatbecause the two conjugates differ in their point of attachment to thecocaine molecule, the specificity of the recognition increases.Specificity of the induced antisera is then confirmed by competitionELISA.

Still further, therapeutic compositions containing more than oneconjugate stimulate polyclonal antibodies thereby enhancing antibodyresponse upon subsequent challenge.

Dose

Neutralizing antibody responses against pathogens are known to last foryears, and it should be possible to achieve a high-titer anti-cocaine oranti-nicotine antibody response that is maintained for at least a year.Based on values obtained with conventional vaccines, it should bepossible to achieve the concentrations of specific antibody required toneutralize cocaine plasma concentrations (1-10 μM); the pharmacokineticdata in mice, described in the Examples, clearly demonstrates thatphysiologically relevant neutralizing antibody concentrations can beachieved. Finally, the ability of maternal antibodies to cross theplacenta in women addicted to cocaine and/or women who smoke, and thusprotect the fetus, represents a further desirable effect of therapeuticcocaine and/or nicotine vaccination. Optimizing therapy to be effectiveacross a broad population is always challenging yet those skilled in theart use a careful understanding of various factors in determining theappropriate therapeutic dose. Further, antibody responses could bemonitored using specific is ELISAs as set out in the Examples and otherantibody based assays.

Genetic variation in elimination rates, interactions with other drugs,disease-induced alterations in elimination and distribution, and otherfactors combine to yield a wide range of response to vaccine levels inpatients given the same dose. Clinical indicators assist the titrationof some drugs into the desired range, and no chemical determination is asubstitute for careful observations of the response to treatment.Because clearance, half-life accumulation, and steady state plasmalevels are difficult to predict, the measurement of anti-drug-of-abuseantibody production is useful as a guide to the optimal dose. Each ofthe conjugates/carriers/adjuvants of the present invention is evaluatedfor the ability to induce an antibody response that is best able to bindfree cocaine or free nicotine in the circulation.

Further details about the effects of carriers and adjuvants on theinduction of an antibody response are given in the Examples.

Thus, it will be appreciated that the actual preferred amounts of activecompound in a specific case will vary according to the specificconjugate being utilized, the particular compositions formulated, themode of application, and the particular sites and organism beingtreated. For example, in one embodiment, the therapeutic compositioncontaining a suitable carrier, is given first parenterally and boostedmucosally. As is discussed in more detail herein, this type ofimmunization with the optimal hapten and carrier combination is veryeffective in generating primarily IgG systemically and primarily IgAlocally.

As set out in the Examples murine models have been used to demonstrateand measure different characteristics of the is antibody response,including antibody titer, ability to recognize free cocaine, cocainebinding capacity, affinity for cocaine, specificity of the antibodyresponse, antibody isotype, antibody tissue localization, and thephysiological effects of the antibody following cocaine administration.

Antibody Titer

The first screen for vaccination is whether the conjugate of interestinduces a high titer antibody response. Antibody titers are determinedusing an ELISA assay as described in the Examples below. Plates arecoated with a cocaine-HEL conjugate, washed extensively, and incubatedwith varying dilutions of the test serum. The plates are again washedand developed with an enzyme-labelled anti-mouse IgG second antibody.Titers are n defined as the reciprocal of the dilution of serum thatgives 50% of the maximal response.

Antibody titer depends on both the concentration of antibody and on theantibody affinity. As detailed in the Examples, antisera with about 0.7mg/ml cocaine-specific antibody of median affinity of about 2×10⁻⁸ M (or5×10⁷/M⁻¹) had an ELISA titer of 80,000. In estimating required antibodytiter, both the concentration and the affinity of the antibodies areconsidered by those skilled in the art.

Although other methods of calculating appropriate antibody concentrationare well known to those skilled in the art, without intending to limitthe invention, one method of predicting anti-cocaine antibodyconcentration requirements is disclosed. Published peak plasma levels ofcocaine in addicts are in the range of 0.3-1.5 μg/ml (Ambre et al.(1991) J. Anal. Tox. 15:17-20; Cone (1995) J. Anal. Tox. 19:159-478; andCone et al. (1989) J. Anal. Tox. 13:65-68). Therefore, 0.075-0.375 mg/mlantibody is close to molar equivalence (The weight ratio of monoclonalantibody/cocaine=approximately 160,000/303=approximately 500 but thereare two binding sites on each antibody, so the molar ratio for bindingsite to cocaine is about 250). It is possible to achieve this level ofantibody response with haptenated carrier, as demonstrated in theExamples. However, if a drug-of-abuse-specific dimeric secreted-form IgAresponse is induced in the mucosa, as disclosed in at least oneembodiment herein, the antibody concentration requirement on a molarbasis is two-fold less relative to drug-of-abuse. It is not implied herethat molar excess of antibody over drug-of-abuse is needed forsuccessful therapy.

In one therapeutic composition of the instant invention,cocaine-specific antibody (monoclonal antibody) blocked the effects of amolar excess of cocaine in a rat addiction model. Rats were injectedwith 4 mg monoclonal antibody before infusion of cocaine (1 mg/kg; 3001g/rat). The measured concentration of monoclonal antibody in the ratswas estimated to be about 80 μg/ml. The antibody was at less than molarequivalence to the cocaine when compared either in the whole animal orin the plasma.

Antibody affinity reflects the amount of antibody-drug complex atequilibrium with unbound antibody and unbound drug-of-abuse, thus:

Keq=[Ab+drug complex]/[Ab]×[drug]

where (Ab)=molar concentration of unoccupied antibody binding sites;[drug]=molar concentration of unbound drug; and [Ab+drug]=molarconcentration of antibody-drug complex.

For example, based on calculations, antibodies with affinity for cocaineabove 10⁻⁶ M are mostly bound to, cocaine and antibodies with affinitiesof about 10⁻⁷ M and are nearly all bound to cocaine at the expectedantibody and cocaine plasma concentrations.

Ability to Recognize Free Cocaine

Once a conjugate is capable of inducing a high-titer serum antibodyresponse, the serum also is tested for its ability to recognize freecocaine in a competition ELISA as described in the Examples. An ELISAassay is set up using a suboptimal dilution of serum. Varyingconcentrations of free cocaine are added along with the antiserum, andthe ELISA is developed as above. Data is expressed as she concentrationof free cocaine required to compete 50% of the antibody binding, anapproximate measure of affinity. Lidocaine, among others, is used as anegative control in the competition experiments, and the cocaine-carrierconjugate that was used in the immunization is used as a positivecontrol.

In addition to the competition ELISA assay, binding is assessed usingradiolabelled cocaine. The data resulting from such assays can indicateif the immune serum is binding to free cocaine. Similar assays are usedto determine binding of nicotine specific antibodies. This is discussedin more detail in the Examples.

Specificity of Antibody Response

In order to be maximally effective at blocking the activity of cocaine,the induced antibodies must have minimal affinity for pharmacologicallyinactive metabolites of cocaine. Binding of antibodies topharmacologically inactive metabolites of cocaine would reduce thepotency of the vaccine. The primary inactive metabolites are ecgoninemethyl ester and to benzoylecgonine each of which is commerciallyavailable. The specificity of the antisera for each of these metabolitesis determined in a competition ELISA and by radiolabelled immunoassay.Furthermore, the effectiveness of the vaccine is increased if theinduced antibodies bind to the pharmacologically active metabolites andderivatives of cocaine. The active metabolite of cocaine is norcocaine.The primary active derivative of cocaine is cocaethylene, formed by invivo transesterification of cocaine, following co-administration ofcocaine and ethanol. This is discussed in more detail in the Examples,below.

Additionally, interaction of the antibodies raised with other drugs usedin addiction therapy and in other medical procedures should beminimized. In particular, cross reaction with drugs n commonlyprescribed to cocaine and poly drug abusers is avoided. While the uniquenature of the cocaine tropane ring structure minimizescross-reactivities, they can be readily tested in a competition ELISA.Indeed, lidocaine is used as a negative control in our competitionELISA. The following drugs are useful as co-treatments, buprenorphine,desipramine, naloxone, haloperidol, chlorproazine, mazindol andbromocriptine, as well as others that may become relevant.

Effect on Cocaine LD₅₀

Those conjugates and immunization protocols that are most effective atinducing high titer specific antibody responses are further evaluatedfor their ability to shift the cocaine LD₅₀. In these experiments,cocaine-immunized and control carrier-immunized mice are injected i.v.with cocaine at doses around the previously defined LD₅₀. Ten mice areused at each point, and the data is analyzed using aCochran-Mantel-Haenzel Chi-squared test.

In addition, a failure time model is used to analyze the time-to-deathinduced by cocaine. The extent to which the anti-cocaine antibodiesincrease both (a) the dose of cocaine is required for lethality and (b)the time-to-death are measures of efficacy in this model. These providea rapid and rigorous test of the in vivo efficacy of the antibodies.

Observing the Physiological Effect on Humans

A person who seeks medical attention during an episode of abuse mightpresent with a rapid pulse, an increased respiratory rate and anelevated body temperature. At high levels of overdose, the pictureprogresses to grand mal convulsions, markedly elevated blood pressure,and a very high body temperature, all of which can lead tocardio-vascular shock. In addition to blood levels, all these factorswill be assessed and specific criteria will be established whenadministration of either active immunization with the vaccine or passiven administration of antibodies to humans in contemplated.

When embodiments of the invention were tested on mice, immunization witha protein-cocaine conjugate induced an antibody response that shifts theLD₅₀ for cocaine (FIGS. 11 a & b). It is hypothesized that therelatively small shift that was observed at very high doses of cocainetranslates into a more dramatic shift at lower cocaine concentrations;the dramatic effect of the anti-cocaine monoclonal antibody on cocaineself-administration is consistent with this hypothesis.

Without intending to limit the scope of the invention, the compositionand methods of this invention will now be described in detail withreference to a preferred drug of abuse, cocaine, and specificembodiments.

Unless otherwise indicated in the Examples, female BALB/c mice of 2-3months of age are used in these studies. These animals have a welldefined reproducible response to the antigens under investigation.Animals are, immunized either intramuscularly, subcutaneously,intratracheally, is intragastrically, or intranasally with aprotein-cocaine conjugate either in saline, or on alum, or in CFA.Unless otherwise noted, BALB/c mice are immunized s.c. with 50 μg oftest conjugate. After 14 days, mice are boosted with the same dose. Inmice immunized using CFA, IFA was used for the subsequent immunizations.Antibody responses in the serum are measured after an additional 14days. Five mice are used per group and all sera are tested individually.CTB used in the following examples is commercially available, forexample, from List or Sigma, or from SBL Vaccin.

Many of the following Examples specifically describe cocaine and ananti-cocaine antibody. These examples are, however, applicable tonicotine. For example, monitoring of the redistribution of nicotine(i.e., diminished amount in the brain) is arrived at by injection ofimmunized mice with the tritium labelled nicotine (available from NEN),followed by decapitation at various time points. The effect of theanti-nicotine antibody on nicotine metabolism and clearance can beanalyzed either by TLC analysis of plasma taken from ³H nicotineinjected mice or by HPLC.

It is to be understood that the example and embodiments described hereinare for purposes of illustration only, and that various modification inlight thereof will be suggested to persons skilled in the art.Accordingly, the following non-limiting Examples are offered forguidance in the practice of the instant invention.

Example 1 Synthesis of PS-2

A solution of ecgonine methyl ester hydrochloride (50 mg, 0.21 mmol),diisopropylethylamine (80 Ill, 0.46 mmol) in DMF (3 ml) was treated withbromoacetyl bromide (22 μl, 0.25 mmol) and heated at 40° C. overnight.The solvents were removed under reduced pressure and the residuepurified by silica gel flash chromatography (9:1 chloroform:methanol asthe eluent), furnishing the bromo compound (67 mg, 96%) as a pale yellowpowder(3β-(Bromoacetyloxy)-8-methyl-8-azabicyclo[3.2.1]octane-2β-carboxylicacid methyl ester).

To a solution of the bromo compound (17 mg, 0.053 mmol) in PBS (0.5 ml),thiolated BSA (15 mg) in PBS (0.5 ml) was added and stirring continuedat ambient temperature for 3 days. The conjugate was purified bydialysis against PBS and then analyzed n by mass spectral analysis.

Example 2 Synthesis of PS-4

To a solution of ecgonine methyl ester (32 mg, 0.16 mmol) in DMF (2 ml),triethylamine (22 μl, 0.16 mmol), followed by succinic anhydride (16 mg,0.16 mmol) was added and the solution heated at 35 C for 2 hours. Thesolvent was removed under reduced pressure and the residue purified bysilica gel flash chromatography (9:1 chloroform:methanol as the eluent).This furnished the desired hemisuccinate (21 mg, 44%) as a white powder(313-(Succinoyloxy)-8-methyl-8-azabicyclo[3.2.1]octane-2,3-carboxylicacid methyl ester).

To a solution of the hemisuccinate (2.4 mg, 7.69 μmol) in distilledwater (0.5 ml) at 0° C., EDC (1.5 mg, 7.69 μmol) was added. After 10minutes, BSA (2 mg in 0.5 ml PBS) and the solution allowed to warm toambient temperature overnight. The conjugate was purified by dialysisagainst PBS and the degree of to haptenation determined by mass spectralanalysis.

Example 3 Synthesis of PS-5 Method A

A solution of norcocaine hydrochloride (1 g, 3.07 mmol), triethylamine(0.86 ml, 6.14 mmol) in methylene chloride (20 ml) was treated withsuccinic anhydride (614 mg, 6.14 mmol) and the mixture heated at 45° C.overnight. The solvents were removed under reduced pressure and theresidue purified using silica gel flash chromatography (2:1chloroform:methanol as the eluent). This gave succinylated norcocaine(1.0 g, 84%) as a thick syrup(3β-(Benzoyloxy)-8-succinoyl-8-azabicyclo[3.2.1]octane-2β-carboxylicacid methyl ester).

To a solution of the acid (14 mg, 0.036 mmol) in distilled water (1 ml)at 0° C., EDC (10.4 mg, 0.055 mmol) was added. After 5 minutes asolution of BSA (14 mg) in PBS (1 ml) was added dropwise and the mixtureallowed to warm to ambient temperature overnight. The conjugate waspurified by dialysis against PBS and the degree of conjugation analyzedby mass spectral analysis.

Method B

To a solution of BSA (500 mg) in 0.2 M borate buffer (80 ml), succinicanhydride (270 mg, 2.70 mmol) in 1,4-dioxane (10 ml) was added in 200 μlaliquots over 30 minutes. The pH was maintained at 9.3 by addition of 3N sodium hydroxide solution. The solution was kept at ambienttemperature for 18 hours, dialyzed against 0.01 M triethylamine and thenlyophilized to yield 583 mg of a fluffy white powder. Mass spectralanalysis of the product indicated 55 succinoyl groups per BSA molecule.

A solution of succinylated BSA (72 mg) in 0.1 M sodium bicarbonatebuffer, pH 8.8 (15 ml) at 0° C. was treated with EDC (88 mg, 0.46 mmol).After 5 minutes, norcocaine hydrochloride is (100 mg, 0.31 mmol) wasadded and the solution allowed to warm to ambient temperature overnight.The conjugate solution was purified by dialysis against PBS and thedegree of haptenation determined by mass spectral analysis.

Example 4 Synthesis of PS-6

To a solution of benzoyl ecgonine (276 mg, 0.96 mmol) in DMF (5 ml) at−10° C., borane-dimethylsulfide complex (1.0 M solution in methylenechloride; 1.0 ml, 1.01 mmol) was added dropwise. This was allowed towarm to ambient temperature overnight, after which the reaction wasquenched by the addition of THF:water (1:1 ratio v/v) followed bystirring for a further 10 minutes. The solvents were removed underreduced pressure and the residue purified using silica gel flashchromatography (chloroform followed by methanol as eluents). Thisfurnished the desired alcohol (246 mg, 93%) as a white powder(3β-(Benzoyloxy)-2β-(hydroxymethyl)-8-methyl-8-azabicyclo[3.2.1]octane).

To a solution of the alcohol (190 mg, 0.69 mmol) in DMF (5 ml),triethylamine (0.19 ml, 1.38 mmol) was added, followed by succinicanhydride (138 mg, 1.38 mmol) and heated at 40° C. overnight. Thesolvents were removed under reduced pressure and the residue purifiedusing silica gel flash chromatography (1:1 chloroform:methanol as theeluent). This furnished the hemisuccinate (123 mg, 48%) as a whitepowder (31-(Benzoyloxy)-2β-(hydroxymethylsuccinoyl)-8-methyl-8-azabicyclo[3.2.1]octane).

To a solution of the hemisuccinate (16 mg, 0.043 mmol) in distilledwater (0.5 ml) at 0° C., EDC (12 mg, 0.064 mmol) was added. After 5minutes, BSA (16 mg) in PBS (0.5 ml) was added dropwise and the solutionallowed to warm to ambient temperature overnight. The conjugate solutionwas purified by dialysis against PBS and the degree of haptenationdetermined by mass spectral analysis.

Example 5 Synthesis of PS-9

To a solution of benzoyl ecgonine (10 mg, 0.035 mmol) in distilled water(1.0 ml) at 0° C., EDC (10 mg, 0.052 mmol) was added. After 5 minutesBSA (10 mg) in PBS (0.5 ml) was added dropwise and the solution warmedto ambient temperature overnight. The protein conjugate was purified bydialysis against PBS buffer. The degree of haptenation was determined bymass spectral analysis.

Example 6 Synthesis of CTB-PS-5 Method A

To a solution of succinylated norcocaine (2 mg, 5.14 μmol) in DMF (0.1ml), diisopropylethylamine (2 μl, 10.3 μmol) was added followed by HATU(2 mg, 5.40 μmol). After 10 minutes, the pale yellow solution was addeddropwise to a solution of CTB (0.5 mg in 0.9 ml of 10 mM borate bufferat pH 7.8) and shaken at ambient temperature for 1.5 hours. The pH ofthe conjugate solution was adjusted to pH 6.5 by the careful addition of1 N HCl, followed by purification by dialysis against 20 mM sodiumsuccinate, pH 6.5. The dialysate was filtered through a 0.2 μm filterand the level of haptenation measured by mass spectral analysis or UVabsorbance.

Method B

To a solution of succinylated norcocaine (2 mg, 5.14 μmol) in DMF (0.1ml), diisopropylethylamine (2 μl, 10.3 μmol) was added followed by HBTU(1.9 mg), 5.40 μmol). After 10 minutes, the pale yellow solution wasadded dropwise to a solution of CTB (0.5 mg in 0.9 ml of PBS buffer atpH 7.6) and shaken at ambient temperature for 1.5 hours. The pH of theconjugate solution was adjusted to pH 6.5 by the careful addition of 1 NHCl, followed by purification by dialysis against 20 mM sodiumsuccinate, pH 6.5. The dialysate was filtered through a 0.2 μm filterand the level of haptenation measured, by mass spectral analysis or UVabsorbance.

Method C

To a solution of succinylated norcocaine (2 mg, 5.14 μmol) in DMF (0.1ml), diisopropylethylamine (2 μl, 10.3 μmol) was added followed by TNTU(1.9 mg, 5.40 μmol). After 10 minutes, the pale yellow solution wasadded dropwise to a solution of CTB (0.5 mg in 0.9 ml of PBS buffer atpH 7.6) and shaken at ambient temperature for 1.5 hours. The pH of theconjugate solution was adjusted to pH 6.5 by the careful addition of 1 NHCl, followed by purification by dialysis against 20 mM sodiumsuccinate, pH 6.5. The dialysate was filtered through a 0.2 μm filterand the level of haptenation measured by mass spectral analysis or UVabsorbance.

Method D

To a solution of succinylated norcocaine (2 mg, 5.14 μmol) in DMF (0.1ml), diisopropylethylamine (2 μl, 10.3 μmol) was added followed by TNTU(1.9 mg, 5.40 μmol). After 10 minutes, the pale yellow solution wasadded dropwise to a solution of CTB (0.5 mg in 0.9 ml of 10 mM boratebuffer at pH 7.8) and shaken at ambient temperature for 1.5 hours. ThepH of the conjugate solution was adjusted to pH 6.5 by the carefuladdition of 1 N to HCl, followed by purification by dialysis against 20mM sodium succinate, pH 6.5. The dialysate was filtered through a 0.2 μmfilter and the level of haptenation measured by mass spectral analysisor UV absorbance.

Method E

To a solution of succinylated norcocaine (2 mg, 5.14 μmol) in DMF (0.1ml), diisopropylethylamine (2 μl, 10.3 μmol) was added followed byPyBroP (2.4 mg, 5.40 μmol). After 10 minutes, the pale yellow solutionwas added dropwise to a solution of CTB (0.5 mg in 0.9 ml of PBS bufferat pH 7.6) and shaken at ambient temperature for 1.5 hours. The pH ofthe conjugate solution was adjusted to pH 6.5 by the careful addition of1 N HCl, followed by purification by dialysis against 20 mM sodiumsuccinate, pH 6.5. The dialysate was filtered through a 0.2 μm filterand the level of haptenation measured by mass spectral analysis or UVabsorbance.

Method F

To a solution of succinylated norcocaine (2 mg, 5.14 μmol) in DMF (0.1ml), diisopropylethylamine (2 μl, 10.3 μmol) was added followed byPyBroP (2.4 mg, 5.40 μmol). After 10 minutes, the pale yellow solutionwas added dropwise to a solution of CTB (0.5 mg in 0.9 ml of 10 mMborate buffer at pH 7.8) and shaken at ambient temperature for 1.5hours. The pH of the conjugate solution was adjusted to pH 6.5 by thecareful addition of 1 N HCl, followed by purification by dialysisagainst 20 mM sodium succinate, pH 6.5. The dialysate was filteredthrough a 0.2 filter and the level of haptenation measured by massspectral analysis or UV absorbance.

Method G

To a solution of succinylated norocaine (4 mg, 0.010 mmol) in dry DMF(0.22 ml), diisopropylethylamine (4 μl, 0.023 mmol) was added, followedby addition of HATU (4 mg, 0.010 mmol). After minutes at ambienttemperature, the resulting pale yellow solution was added dropwise torCTB (1 mg) in 0.1 M sodium borate, 0.15 M sodium chloride, pH 7.8 (2ml). The resulting is clear colorless solution was gently agitated for1.5 hours at ambient temperature and then dialyzed against 20 mM sodiumsuccinate, pH 6.5 at 4° C. The resulting conjugate was analyzed by GM1capture ELISA, reverse phase HPLC and mass spectral analysis.

Method H

To a solution of succinylated norocaine (1 mg, 0.026 mmol) in dry DMF(0.22 ml), diisopropylethylamine (1 μl, 0.0052 mmol) was is added,followed by addition of HATU (1 mg, 0.0031 mmol). After 10 minutes atambient temperature, the resulting pale yellow solution was addeddropwise to rCTB (1 mg) in 0.1 M sodium borate, 0.15 M sodium chloride,pH 7.8 (2 ml). The resulting clear colorless solution was gentlyagitated for 1.5 hours at ambient temperature and then dialyzed against20 mM sodium succinate, pH 6.5 at 4° C. The resulting conjugate wasanalyzed by GM1 capture ELISA, reverse phase HPLC and mass spectralanalysis.

Method I

To a solution of succinylated norocaine (0.4 mg, 0.0010 mmol) in dry DMF(0.22 ml), diisopropylethylamine (0.4 μl, 0.0023 mmol) was added,followed by addition of HATU (0.4 mg, 0.001 mmol). After 10 minutes atambient temperature, the resulting pale yellow solution was addeddropwise to rCTB (1 mg) in 0.1 M sodium borate, 0.15 M sodium chloride,pH 7.8 (2 ml). The resulting clear colorless solution was gentlyagitated for 1.5 hours at ambient temperature and then dialyzed against20 mM sodium succinate, pH 6.5 at 4° C. The resulting conjugate wasanalyzed by GM1 capture ELISA, reverse phase HPLC and mass spectralanalysis.

Method J

To a solution of succinylated norocaine (0.1 mg, 0.00010 mmol) in dryDMF (0.22 ml), diisopropylethylamine (0.1 μl, 0.00052 mmol was added,followed by addition of HATU (0.1 mg, 0.0010 mmol). After 10 minutes atambient temperature, the resulting pale yellow solution was addeddropwise to rCTB (1 mg) in 0.1 M sodium borate, 0.15 M sodium chloride,pH 7.8 (2 ml). The resulting clear colorless solution was gentlyagitated for 1.5 hours at ambient temperature and then dialyzed against20 mM sodium succinate, pH 6.5 at 4° C. The resulting conjugate wasanalyzed by GM1 capture ELISA, reverse phase HPLC and mass spectralanalysis.

Method K

To a solution of succinylated norocaine (40 mg, 0.10 mmol) in dry DMF(0.22 ml), diisopropylethylamine (40 μl, 0.23 mmol) was added, followedby addition of HATU (40 mg, 0.10 mmol). After 10 minutes at ambienttemperature, the resulting pale yellow solution was added dropwise via apressure equalizing dropping funnel to rCTB (100 mg) in 0.1 M sodiumborate, 0.15 M sodium chloride, pH 8.5 (200 ml). The resulting clearcolorless solution was gently agitated for 1.5 hours at ambienttemperature and then diafiltered against 0.1 M ammonium bicarbonate, pH8.5 at room temperature. Lyophilization afforded the buffer-freeconjugate as a white powder, which was analyzed by GM1 capture ELISA,reverse phase HPLC and mass spectral analysis.

Method L

To a solution of succinylated norocaine (4 mg, 0.010 mmol) in dry DMF(0.44 ml), diisopropylethylamine (4 μl, 0.023 mmol) was added, followedby addition of HATU (4 mg, 0.010 mmol). After 10 minutes at ambienttemperature, the resulting pale yellow is solution was added dropwise torCTB (1 mg) in 0.1 M sodium borate, 0.15 M sodium chloride, pH 7.8 (2ml). The resulting clear colorless solution was gently agitated for 1.5hours at ambient temperature and then dialyzed against 20 mM sodiumsuccinate, pH 6.5 at 4° C. The resulting conjugate was analyzed by GM1capture ELISA, reverse phase HPLC and mass spectral analysis.

Method M

To a solution of succinylated norocaine (1 mg, 0.0026 mmol) in dry DMF(0.44 ml), diisopropylethylamine (1 μl, 0.0052 mmol) was added, followedby addition of HATU (1 mg, 0.0031 mmol). After 10 minutes at ambienttemperature, the resulting pale yellow solution was added dropwise torCTB (1 mg) in 0.1 M sodium borate, 0.15 M sodium chloride, pH 7.8 (2ml). The resulting clear colorless solution was gently agitated for 1.5hours at ambient temperature and then dialyzed against 20 mM sodiumsuccinate, pH 6.5 at 4° C. The resulting conjugate was analyzed by GM1capture ELISA, reverse phase HPLC and mass spectral analysis.

Example 7 Alternative Syntheses of CTB-PS-5 Method A

A solution of succinylated norcocaine (15 mg, 0.39 mol), thionylchloride (28 μl, 0.39 mmol) in DMF (250 μl) was stirred at ambienttemperature for 2 hours. After the reaction was deemed complete (by TLCanalysis), the solvents were removed under reduced pressure and theresulting chloro derivative(3β-(Benzoyloxy)-8-chlorosuccinoyl-8-azabicyclo[3.2.1]octane-2β-carboxylicacid methyl ester) taken through to the next step without furtherpurification.

The chloro derivative (16 mg, 0.04 mmol) was dissolved in DMF (100 μl)and added dropwise to a solution of CTB (0.38 mg/ml in 3 ml PBS). Theresulting mixture was kept at ambient temperature overnight, dialyzedagainst PBS and the degree of haptenation determined by mass spectralanalysis.

Method B

To a solution of succinylated norcocaine (100 mg, 0.26 mmol) in DMF (5ml), DCC (64 mg, 0.31 mmol) was added. After 10 minutes,4-hydroxy-3-nitrobenzene sulfonic acid sodium salt (74 mg, 0.31 mmol)was added and the resulting yellow solution kept at ambient temperaturefor 4 days. The resulting suspension was filtered under reduced pressureand the filtrate added to cold diethyl ether (10 ml) with vigorousstirring. Hexane (5 ml) added and after complete precipitation of ayellow oil, the colorless supernatant was decanted off. This process wasrepeated and the oil dried overnight under reduced pressure, furnishingthe desired ester (157 mg) (3β-(Benzoyloxy)-8-(2-nitro-4-sulfophenylester)succinoyl-8-azabicyclo[3.2.1]octane-2β-carboxylic acid methylester) which was taken through to the next stage without furtherpurification.

The ester (5 mg, 8.16 μmol) was dissolved in DMF (100 μl) and addeddropwise to CTB (1 mg in 2 ml PBS) at 4° C. and then warmed to ambienttemperature. After 3 hours the conjugate solution was purified bydialysis against PBS and the degree of haptenation determined by massspectral analysis.

Method C

To a solution of succinylated norcocaine (108 mg, 0.28 mmol) in DMF (5ml) at 0° C., NMM (37 μl, 0.33 mmol) followed by ethyl chlorofomate (32μl, 0.33 mmol) were added. After 10 minutes, N-hydroxysuccinimide (38mg, 0.33 mol) was added and the solution warmed to ambient temperatureover 18 hours The solvents were removed under reduced pressure and theresidue recrystallized from isopropanol/diethyl ether to furnish theN-oxysuccinimidyl ester (113 mg, 84%) as a white powder(3β-(Benzoyloxy)-8-(N-oxysuccinimidoyl)succinoyl-8-azabicyclo[3.2.1]octane-2β-carboxylicacid methyl ester).

A solution of the ester (2 mg, 4.11 μmol) in DMF (100 μl) was addeddropwise to a solution of CTB (1 mg in 2 ml PBS). After 3 days theconjugate solution was purified by dialysis against PBS and the degreeof haptenation determined by mass spectral analysis.

Example 8 Synthesis of a Conjugate with an Extended Spacer

To a solution of norcocaine hydrochloride (50 mg, 0.15 mmol) in DMF (1ml), diisopropylethylamine (27 μl, 0.31 mmol) was added. After 5 minutesthe solution was cooled to 0° C. and added dropwise to a solution ofadipoyl chloride (44 μl, 0.080 mmol) in DMF (100 μl) at 0° C. After 2hours the solution was added dropwise to a solution of CTB (1 mg in 2 mlPBS) at 0° C. and warmed to ambient temperature overnight. The conjugatesolution was purified by dialysis against PBS and the degree ofhaptenation determined by mass spectral analysis.

Example 9 Conjugation of Succinylated Norcocaine with MAP

MAP resin (Novabiochem USA, La Jolla, Calif.) (substitution level: 0.48mmol/g: 50 mg, 0.023 mmol) was pre-swollen in DMF (5 ml). The solventwas decanted and the resin treated with a w solution of 20% piperidinein DMF (5 ml), agitated for 15 minutes and the solvents removed bydecanting. The resin was washed sequentially with DMF (5 ml), methanol(5 ml) and DMF (5 ml). A solution of succinylated norcocaine (18 mg,0.046 mmol) in DMF (1 ml) was treated with a mixture of HOBt/DMF/HATU(0.5 M is freshly prepared solution in DMF; 92 μl, 0.046 mmol) and after5 minutes, this was agitated overnight after which the reaction wasdeemed to be >90% complete by the Kaiser-Ninhydrin test. The solventswere decanted off and the resin beads washed exhaustively with methanol,followed by drying under a stream of argon. The derivatized MAP wascleaved by suspending the resin in 2.5% phenol/TFA/EDT (5 ml) andagitating for 1 hour, filtered, washed with TFA (4×4 ml) and thesolvents removed under reduced pressure. The crude peptide wastriturated with cold diethyl ether, centrifuged for 5 minutes at 5000rpm and is the process repeated. The pellet was dissolved in water andlyophilized to give 1 mg of crude peptide.

Example 10 Synthesis of (N-succinamidyl-cocaine)₈-MAP Protein Conjugate

Synthesis of the non-hapten portion (MAP core) of the poly-haptenatedMAP is carried out by manual peptide synthesis as described by Tam et al(U.S. Pat. No. 5,229,490). Amino groups are protected by the Boc(t-butyloxycarbonyl) function and the sulfhydryl group of Cys isprotected as its 3-nitro-2-pyridylsulfenyl (Npys) derivative. Afterassembly on the resin and removal of Boc protecting groups with TFA asdescribed by Tam (supra.), the MAP core is cleaved from the resin by HFcleavage leaving the Npys group intact. Crude MAP core is taken up in 7M guanidine hydrochloride containing 0.2 M HOAc and subjected to gelpermeation chromatography in 0.2 M HOAc on Sephadex G-10 t remove anyremaining low molecular byproducts generated by the HF cleavage. The MAPcore is lyophilized from 0.2 M HOAc. (N-succinamidyl-norcocaine)-8-MAPis prepared according as described in Example 9.

Prior to coupling to activated protein the thiol group is exposed bytreatment with a molar equivalent of tris-(2-carboxyethyl) phosphinehydrochloride (TCEP). Activated protein carrier is dissolved at 5 mg/mlin 0.2 M sodium bicarbonate is buffer at room temperature. To thissolution is added a 2-fold molar excess of(N-succinamidyl-norcocaine)-8-MAP at 5 mg/ml. The reaction is allowed toproceed for 20 hours at room temperature and then dialyzed overnightagainst 0.2 M HOAc and lyophilized.

Example 11 Testing the Induction of Cocaine Specific Antibody Response

In order to induce an antibody response against a small molecule orhapten, such as cocaine, it is necessary to link it to a T cellepitope-containing carrier, e.g., a protein carrier. The carrier isrecognized by T cells which provide help to the cocaine-specific B cellsfor initiation and maintenance of sustained antibody production. In thisexample, the carrier used was BSA, a protein which has 36 lysineresidues that are exposed and available for conjugation. A panel ofstructurally distinct cocaine-protein conjugates were produced that werelinked through different regions of the cocaine molecule (FIGS. 1 a, 1b, 2 a, 2 b). A set of conjugates was synthesized because the cocainemolecule is physically altered and differently oriented during theconjugation process to the carrier. Since any given cocaine conjugatemay induce antibodies which recognize the conjugate only, and not thefree hapten (cocaine) itself, screening was performed.

Mice were immunized with 50 μg of cocaine-BSA conjugate PS-5.1 andPS-5.6 (FIGS. 9 a and b) or with PS-9.1 (FIG. 9 c) i.p. either with CFA(FIGS. 9 a and 9 c) or with alum (FIG. 9 b). Mice were boosted one timeand then bled. The mice immunized with cocaine-BSA conjugate PS-5.1 wereboosted with cocaine-BSA conjugate PS-5.6. Sera were tested in an ELISAassay using plates coated with PS-5 (conjugated to HEL) or PS-9(conjugated to HEL) as appropriate. The responses of 5 individual miceper group are shown. These data demonstrate that the cocaine-BSAconjugates are able to induce high titer antibody responses.

Example 12 Recognition of Free Cocaine

To directly determine whether the induced antibodies were capable ofrecognizing the free cocaine molecule, a competition ELISA wasestablished. Plates were coated with appropriate free cocaine-HELconjugate and incubated with the antisera at a 1:2000 dilution in thepresence of varying concentrations of n free cocaine as competition.When PS-5.6-BSA was used as the immunogen, the majority of the antibodyresponse was effectively competed by free cocaine (FIGS. 10 a and b). Inthis set of sera from ten mice, (each line on the graph in FIG. 10 aindicates a different mouse) one was less effective in the n competitionassay (open squares and dotted line), and this mouse was not used in theLD₅₀ experiments described herein. The PS-9,2-BSA conjugate also inducescocaine-specific antibodies. These data demonstrated thatcocaine-carrier conjugates can be synthesized which induce high-titer,cocaine-specific antibody responses that should be capable ofneutralizing cocaine in vivo.

Example 13 Ability of Vaccination to Protect Against Cocaine Toxicity

The present invention discloses a cocaine-protein conjugate that inducedan anti-cocaine antibody response in a mouse model. These anti-cocaineantibodies neutralized cocaine in vivo, significantly shifting the doseof cocaine required to induce a lethal response in mice.

The efficacy of therapeutic vaccination against cocaine was assessed bydetermining the lethal dose of cocaine (LD₅₀) in immunized and naiveanimals. The prediction was that a strong cocaine-specific antibodyresponse should bind sufficient quantities of cocaine to prevent therapid cardiac, respiratory, and neurological effects of cocaine, thusincreasing the LD₅₀ of cocaine in the immunized mice. Sixty BALB/c micewere immunized with 50 μg PS-5.4-BSA in CFA and boosted only once withthe same conjugate in IFA. Each of the mice was bled at day 34 and serumantibody titers and competition with cocaine were assessed. Forty-eightmice were chosen for the experiment, with average titers of 18,700, allof which displayed competition with free cocaine. For the LD₅₀experiment, 4-6 mice were used per group and each group was carefullymatched for antibody titer and apparent affinity for free cocaine.

As shown in FIG. 11, the LD₅₀ for cocaine in naive BALE/c mice was 3mg/kg when the drug was given intravenously (i.v., FIG. 11 b) and 20mg/kg when given intraperitoneally (i.p., FIG. 11 a). Immunization ofmice with the cocaine-protein conjugate changed the LD₅₀ significantly.The doses required for half-maximal toxicity were 4.5 mg/kg and 35 mg/kgfor the i.v. and i.p. doses, respectively. These doses weresignificantly different from the value obtained in the naive mice(p=0.048 for i.v. and p=0.014 for i.p., Cochran-Mantel-HaenszelChi-squared test). The almost two-fold protection of acute high dosetoxicity by cocaine vaccination compares favorably with some drugsaffecting cocaine pharmacology. For example, the NMDA antagonist MK-801increased the LD₅₀ 1.3-fold and 1.4-fold when combined with propanolol(Itzhak et al. (1992) J. Pharmacol. Exp. Therap. 262:464-467). Inaddition, vaccination significantly prolonged the time to death from anaverage of 3.2 min to 5.4 min. for i.v. administration (p=0.007,Wilcoxon 2-sample test) and from 4.0 min to 8.5 min. for i.p.administration (p=0.0003). This study demonstrates that the antibodyaffected the in vivo physiological response to high dose cocaine.

Example 14 Discrimination of Cocaine from Saline in Rat Model

To demonstrate the stability and reproducibility of this system, 8 ratsare trained to discriminate i.p. injections of 10 mg/kg cocaine fromsaline using a 2-lever procedure (Kantak et al. (1995) J. Pharmacol.Exp. Therap. 274:657-665). After cocaine injections are given, theanimals are required to press one of the levers (drug-appropriate lever)10 times (FR 10) to obtain a food pellet; upon saline injections, theyare required to press the other lever (saline-appropriate lever) 10times to obtain a food pellet. When animals have learned to discriminatecocaine from saline, at least 90% of the total responses are made on theappropriate lever for several consecutive days. In order to incorporatea cumulative dosing procedure during later substitution test sessions,training sessions are made up of multiple components, each lasting for10 min or until 10 FRs are completed, whichever occurred first.

Following training, substitution test sessions with different doses ofcocaine (0.3-17.8 mg/kg) are conducted twice weekly, with trainingsessions on intervening days. Drug substitution test sessions consistedof four 10 min components, each preceded by a 15 min time-out period.During substitution tests, completion of 10 responses on either leverproduce a food pellet. Incremental doses of cocaine are injected at thebeginning of each of the 4 time-out periods. Overlapping ranges ofcumulative doses are studied on different test days, permitting aseven-point cumulative dose-response curve to be determined in a singleweek.

In substitution tests, cocaine engendered dose-related increases in thepercentage of cocaine-appropriate responses, which result in fullsubstitution (>90% cocaine-appropriate responses) for all subjects afteradministration of doses that are at least the level of the trainingdose. Each data point is based on 2-3 determinations in individualsubjects. The ED50±95% C.I. for cocaine-appropriate responses is2.14±0.20 mg/kg, which is compares favorably to the value obtained inrats trained to discriminate injections of 10 mg/kg cocaine using singlecomponent and single dosing procedures (2.6±0.29 mg/kg; (Kantak et al.(1994) J. Pharmacol. Exp. Ther. (under review)).

Example 15 Assays to Detect the Function Activity of CTB

To test the functional activity of CTB alone, two assays were developed.First, binding of CTB to cells was measured using flow cytometry. Cellswere incubated with CTB, followed by a commercial anti-CTB goatantiserum and a fluorescein isothiocyanate (FITC)-labelled anti-goatsecondary antibody (FIG. 13). Native pentameric CTB bound to the cells,causing a dramatic shift in fluorescence intensity. Monomeric CTB was nunable to bind to cells in this assay. Second, an ELISA was set up tomeasure the ability of the CTB to bind to ganglioside GM1. ELISA plateswere coated with GM1-ganglioside and incubated with varyingconcentrations of CTB. Binding was detected using an anti-CTB antibody(or saline as a control) followed by enzyme-55 labelled second antibodyand development with substrate. This assay provided a quantitative andextremely sensitive measure of the ability of pentameric CTB to bind toGM1 gangliosides. These assays are used to monitor the functionalactivity of recombinant and haptenated CTB conjugates prior toexperiments in vivo. Similarly, FIG. 14 a shows that conjugation doesnot affect the ability of CTB-specific antibodies to recognize theconjugate. FIG. 14 b shows that the conjugated CTB molecules which areable to bind GM1 can also be bound by cocaine-specific antibodies,demonstrating the retention of CTB activity by haptenized CTB.

Example 16 Self-Administration Model of Addiction and Effect of Vaccine

In rats, the reinforcing stimulus properties of cocaine can be studiedreliably using intravenous self-administration procedures. This is adirect model of addiction and drug self-administration behavior inanimal subjects which positively correlates with abuse of that drug byhuman subjects. To examine the effect of the therapeutic vaccine, adultmale rats n (Wistar, approximately 300 g) are implanted with a chronicjugular vein catheter using the general procedures described by Weeks(Meth. Psychobiol. (1972) 2:115-168) and as adapted by Kantak et al.(Kantak et al. (1990) Pharm. Biochem. Behavior 36:9-12; (Kantak et al.(1991) Psychopharm. 104:527-535; and Kantak et al. (1992) Pharmacol.Biochem. Behav. 41:415-423). All animals are housed individually andmaintained at 80%-85% of their free feeding body weights to facilitatecomparison with the drug discrimination experiments. One week followingsurgery, 1.0 mg/kg/infusion of cocaine is available as the training dosein daily 2 hr sessions. Rats typically self-infuse a cumulative dose of10 mg/kg each hour. During the initial phase of training, each leverpress results in drug delivery. The required number of responses toself-infuse cocaine is increased gradually to 5 (FR 5) and then the FR5:FI 5 min schedule of drug delivery is introduced. Following stableresponding for at least 5 days, a baseline cocaine dose-response curve(0.1, 0.3, 0.56, 1.0 and 3.0 mg/kg/infusion) is determined. Each dose ofcocaine, as well as saline, is examined for a block of at least 5sessions and until no systematic upward or downward trends in respondingare observed. Data is expressed as mean response rates over the last twodays of each block of sessions.

Following determination of the baseline cocaine dose-response curve in30 rats, half the rats are immunized with the optimal cocaine-carrierconjugate and the other half are immunized with carrier alone.Self-administration sessions are discontinued until significantanti-cocaine antibody titers are achieved, which should take 4-6 weeks.Rats are bled from the tail vein to ensure that all rats have comparabletiters of cocaine-specific antibodies. Following immunization, the ratsare tested for their ability to respond to cocaine. Rats will haveaccess to varying doses of cocaine (0.3-3.0 mg/kg/infusion), or tosaline, in 5-day blocks. Control rats immunized with carrier alonequickly return to the baseline pattern of cocaine self-administration.

To determine if anti-cocaine antibody blocks the reinforcing effects ofcocaine, doses of cocaine up to 30 mg/kg/infusion are examined todetermine how much protection the antibody affords. If the anti-cocaineantibody partially blocks cocaine, the rats require much larger doses ofcocaine to achieve the desired physiological effect and responsesmaintained by cocaine are reinstated with a rightward shift in thecocaine dose-response curve. If the polyclonal cocaine antibodycompletely blocks doses of cocaine up to 30 mg/kg/infusion, thenresponding which is maintained by cocaine is not reinstated and cocaineself-administration extinguishes, with the cocaine dose-response curveremaining flat at near-zero saline-like levels.

Cocaine self-administration can also be inhibited by passivelyadministered anti-cocaine antibody. Monoclonal anti-cocaine antibody orcontrol antibody was administered to separate groups of rats. Animalsthat had been previously stabilized on a FR5:F15 schedule of cocaineadministration extinguished their self-administration of cocaine ifpassively treated with anti-cocaine antibodies. Rats treated withcontrol antibody maintained their cocaine self-administration responses.

Example 17 Co-Treatment with Other Drugs

Screening is done to determine whether pharmacotherapy withbuprenorphine, mazindol, and/or desipramine will enhance the is activityof the therapeutic vaccine. Treatment with buprenorphine, mazindol,and/or desipramine are expected to be compatible. It is possible thatthe therapeutic agents could be immunosuppressive, thus inhibiting theinduction of a high titer anti-cocaine antibody response. To addressthis possibility, rats are immunized with the cocaine-carrier conjugatein the presence or absence of buprenorphine or desipramine and theantibody titer is measured at varying times. A drug which is found to besignificantly immunosuppressive will be eliminated as an incompatibletherapy. This screening test is used for any is drug for whichco-treatment is considered.

If no immunosuppression is seen, further screening is carried out todetermine if the two approaches synergize. Following training,immunization and testing, rats are further evaluated n in the two modelsin the presence of the drugs. Rats will receive drugs before sessionswith different doses of cocaine. Initial experiments with controlcarrier-immunized rats are performed to choose a dose of drug that doesnot completely extinguish behavior in the self-administration or drugdiscrimination systems; it is estimated that this dose is approximately24 μg/kg/day (−)-buprenorphine 20 μg/kg/day mazindol, or 2 mg/kgdesipramine. Data is evaluated to determine whether the action of thetherapeutic vaccine is additive with the treatment with buprenorphine ordesipramine.

Example 18 Induction of Mucosal Response

The B subunit of cholera toxin (CTB) has been shown in many systems toretain the activity of intact cholera toxin, including the induction ofa mucosal antibody response. Therefore, this carrier should induce astrong anti-cocaine or anti-nicotine IgA antibody response. In addition,oral priming should induce a strong systemic IgG antibody response

An effective way to prime an immune response in the respiratory tract isto deliver antigen directly to those sites. The antigen is administeredin saline, with CTB acting as its own adjuvant. To confirm the abilityof CTB to prime by administration at a mucosal IgA surface, initialexperiments are conducted with carrier alone. Mice are primed with 50 μgof the CTB or cocaine-CTB or nicotine-CTB conjugate by three routes:orally, nasally or intratracheally. For oral administration of mice, 250μg of either cocaine-CTB or nicotine-CTB conjugate or CTB alone isapplied intragastrically, or directly to the stomach, through the use ofa blunt 23 G needle. Fourteen days after priming, the mice are boostedusing the same protocol. Nasal administration is a simple and commonroute of priming. Antigen is applied to each nostril of a lightlyanesthetized mouse, for a total volume of 50 μl per mouse. Fourteen daysafter priming, the mice are boosted using the same protocol. Nasaladministration is adaptable readily to human application as a nasalspray. Nasal vaccination has been used successfully with live influenzavaccines (Walker et al. (1994) Vaccine 12:387-399).

Intratracheal immunization directly applies the antigen to the lowerrespiratory tract, thereby enhancing immunity in the lungs. Mice areanesthetized with a cocktail of ketamine and xylazine. The animals aremounted on an apparatus that holds their mouth open and exposes thetrachea; the trachea is visualized with a fiberoptic light probe. Ablunt 23 gauge needle is used to deliver 50 μl of solution into thelungs. Fourteen days after priming, the mice are boosted using the sameprotocol.

Animals are sacrificed by CO₂ asphyxiation at varying time points afterboost (14, 21, or 28 days) and nasal and bronchoalveolar lavage fluidsare collected and assayed for IgA specific for the administeredconjugate. Nasal wash fluid is obtained by washing the nasal cavity fourtimes with a total of 1 ml PBS as described (Tamura et al. (1989)Vaccine 7:257-262). Bronchoalveolar lavage fluid is obtained bysurgically exposing the trachea, injecting 0.5 ml PBS into the lungs,and rinsing three times as described (Nedrud et al. (1987) J. Immunol.139:3484-3492). Following centrifugation to remove cells, samples areassayed for antigen-specific IgA by ELISA using an IgA-specific secondantibody. Cocaine-specific or nicotine-specific IgG is measured in thenasal and lung washes, as it has been reported that IgG is frequentlyboth detectable and important in the lung (Cahill et al. (1993) FEMSMicrobiol. Lett. 107:211-216).

The oral immunization route is evaluated for its ability to generatecocaine-specific or nicotine-specific IgA in intestinal washes and iscompared with other routes for its ability to generate serum Ig specificfor cocaine or nicotine. Oral administration is particularly preferredin humans due to ease of administration. The intranasal andintratracheal routes of administration are compared directly for theirability to induce an IgA response in both the lung or nasal lavagefluid. Whichever route is found to be most potent, it is preferred andused for the remaining experiments. If the two routes are of comparableefficacy, nasal immunization is preferred because of its simplicity.

For maximal protection against cocaine or nicotine, systemic IgG andmucosal IgA responses may both be maximized. Therefore, both a systemicinjection with the cocaine-CTB or nicotine-CTB conjugate in alum (orsome other adjuvant) and a mucosal challenge with the conjugate arepreferred to effectively prime both compartments. Three groups arecompared. First, mice are primed systemically, followed by a mucosalchallenge after 14 days. Second, the mice are primed mucosally, followedby a systemic challenge after 14 days. Third, they are primed bothsystemically and mucosally at the same time, followed by an is identicalboost after 14 days. Control mice are primed only mucosally or onlysystemically. In each case, efficacy in challenge is determined bymeasurement of both IgG and IgA anti-cocaine antibody titers.

As an initial measure of the in vivo efficacy of mucosal anti-cocaine oranti-nicotine antibodies, the change in drug pharmacokinetics ismeasured for mucosally administered cocaine or nicotine, respectively.

Example 19 Immunogenicity of Cocaine-CTB Conjugates A. Definition ofDose Required for Immunogenicity

The immunogenicity of cocaine-CTB conjugates was determined byimmunization of rodents with cocaine-CTB, boosting where appropriate,and assessing antibody levels at varying times. Antibody levels weremeasured in an antigen-specific ELISA. Antibody titers were determinedas the reciprocals of the serum dilution giving 50% of the maximalresponse in the ELISA and are expressed as the geometric means of theresults from 5 or more mice.

To determine the range of antigen dose required to induce ananti-cocaine antibody response, mice were immunized eithersubcutaneously or intramuscularly with varying doses of cocaine-CTBPS-5.53. Animals were boosted on days 23 and 59 and bled on day 71.Doses of 3, 10, and 30 μg given intramuscularly induced titers ofcocaine-specific IgG of 18429, 29013, and 22957, respectively. Usings.c. immunization, the same doses induced specific antibody titers of10097, 15136, and 21169. These data demonstrate that cocaine-CTB can beeffectively used in the range of 3-30 μg and greater and lower doses areexpected to be effective. Similar doses are also effective for use inrats. Those skilled in the art use this data to identify optimal humandoses, which are usually comparable.

B. Immunization on Mucosal Surfaces

To generate optimal antibody responses in mucosal secretions, it isusually necessary to prime at a mucosal surface. To determine whetherCTB would be a useful carrier protein for the induction of a mucosalantibody response, mice were immunized intranasally or intratracheally.The methods for intranasal and intratracheal immunization are describedin Example 18. Intranasal immunization with cocaine-CTB inducedsignificant levels of circulating cocaine-specific IgG, although thetiters were lower than those seen following subcutaneous orintramuscular immunization. As with the routes of administrationdescribed in Part A of this example, doses of cocaine-CTB of 3-30 μg allinduced significant levels of cocaine-specific antibody. Simultaneousimmunization by subcutaneous and intranasal routes induced antibodytiters indistinguishable from those induced by the subcutaneous routealone. The feasibility of the intratracheal route of immunization wasassessed by immunization with CTB alone. This route was also found toinduce antigen-specific IgG in the serum (CTB-specific in this case).These data demonstrate that CTB is capable of inducing a systemicantigen-specific IgG response following immunization at a mucosalsurface in the absence of any added adjuvant.

C. Induction of Cocaine-Specific Antibodies in Mucosal Secretions

To maximize protection against the addictive properties of cocaine, itis desirable to optimize the levels of cocaine-specific antibody at thesites of cocaine application (e.g. nasal and lung mucosa) as well as inthe blood. Mice were immunized intranasally or subcutaneously with 10 μgcocaine-CTB and were boosted using the same protocol on days 27 and 61.Following sacrifice on day 78, bronchial and nasal washes were collectedas described in the Examples and assayed for cocaine-specific IgA andIgG. Anti-cocaine antibodies were detectable in both the nasal andbronchial washes using both immunization n regimens. Intranasalimmunization induced higher levels of antigen-specific IgA, while bothroutes were comparable at inducing anti-cocaine IgG responses in themucosal secretions. The intranasal route of administration was alsofound to be the most effective route for the induction ofantigen-specific IgA in the serum. Intratracheal immunization with CTBalso induced CTB-specific IgA and IgG in the respiratory secretions.These data demonstrate that CTB is an effective carrier protein for theinduction of an antigen-specific antibody response in the respiratorytract.

D. Use of Alum as Adjuvant for Immunization

The use of adjuvant is often beneficial in immunization protocols. Toassess the contribution of alum to the immune response, mice wereimmunized with 10 μg cocaine-CTB PS-5.53 intraperitoneally in saline oradsorbed onto alum. The mice were boosted at day 27 using the sameprotocol. For both groups of animals, high levels of cocaine-specificantibodies were detected by day 43 (titer of 14687 without alum and16775 with alum). Immunization with cocaine-CTB adsorbed onto alum hasalso been shown to be effective with a subcutaneous or intramuscularroute of administration. Therefore, the use of alum is acceptable withthis antigen.

The addition of alum adjuvant can increase the immune response toinjected proteins. Obtaining sufficient antibody titers requires testingthe contribution of alum to the antibody response after injection ofdrug-carrier conjugates. To assess the contribution of alum mice wereimmunized with 10 μg cocaine-rCTB PS-5.189, where the CTB wasrecombinantly expressed in bacteria. The mice were injectedintramuscularly in saline or is absorbed onto alum and again on day 14.For these lots of cocaine-CTB conjugates the addition of alum isrequired in order to generate anti-cocaine antibodies as detected byELISA.

E. Duration of Antibody Responses

To determine whether antibody responses induced with cocaine-CTB

PS-5.8 are long-lasting, serum antibody levels were monitored as n afunction of time. The animals described in section D of this Examplewere monitored out to day 128 after immunization. At that time point,antibody titers remained high, dropping approximately 2-fold from thepeak at day 43. These data demonstrate that anti-cocaine antibodyresponses to cocaine-CTB n conjugate are long-lasting.

F. Relative Levels of Anti-Hapten and Anti-Carrier Antibody Response

Immunization with cocaine-CTB induces an antibody response against boththe hapten (cocaine) and the carrier (CTB). CTB is a very powerfulimmunogen and it is possible that the anti-CTB response could dominate,preventing the anti-cocaine response from reaching very high titers. Todetermine whether it was possible to differentially regulate theanti-cocaine and anti-CTB antibody response to CTB by changing theimmunization regimen, the following nonlimiting test was performed. Micewere intramuscularly immunized with 30 μg cocaine-CTB and monitored forantibody response. This immunization induced both anti-cocaine andanti-CTB antibodies with the relative ratio of the serum IgG titersbeing 0.04. In contrast, a ratio of 0.2 was seen when the mice wereimmunized with 3 μg cocaine-CTB. These doses of 3 μg and 30 μg producesimilar titers of 18429 and 22957, respectively. It is likely that theratio of anti-cocaine to anti-CTB antibodies will also be affected byother is parameters of the immunization regimen as well as by propertiesof the conjugate itself, such as level of haptenation.

Example 20 Direct Binding of Cocaine by Antibodies from Immunized Mice

The ability of the antibodies to bind free cocaine can be assessed usingradiolabelled cocaine. ³H-Cocaine (1 μCi) was incubated with serum fromnormal mice (0.05 ml), with serum from mice immunized with a PS-5.4conjugate (conjugated with BSA) u (0.05 ml, pool of serum from 10 mice)or with commercially available anti-cocaine monoclonal antibodies(mixture of two different antibodies, 2 μg of each) (see FIG. 10 b).Beads coated with protein G were included in the incubation to bind tothe Fc portion of antibody molecules. After 2 hours, the beads werepelleted by centrifugation, washed three times with cold PBS and countedin a scintillation counter. The data in FIG. 10 b represent the mean andstandard deviations of duplicate samples. These data clearly show thatthe immune serum is able to bind free cocaine with an affinitysufficiently high to permit the bound cocaine to be precipitated andwashed. This is evidence that these antibodies will be able to bind andneutralize cocaine in the circulation of cocaine addicts.

Example 21 Specificity of Cocaine-Specific Antibodies

To further analyze the specificity of the cocaine specific antibodiesinduced by the cocaine vaccine, a pool of mice immunized cocaine-CTBconjugate PS-5.53 were tested in a competition ELISA. Different drugswere tested at varying concentrations for their ability to inhibit thebinding of antibodies to cocaine-HEL. The panel of drugs tested includedcocaine, benzoylecgonine (the major metabolite of cocaine); dopamine,serotonin, and norepinephrine (neurotransmitters); is methylphenidateand amphetamine (CNS stimulators); procainamide HCl (a cardiacdepressant); atropine (a compound that has a tropane ring in itsstructure); and lidocaine (a general anesthetic). The pool ofanti-cocaine antisera was specific for cocaine in that cocaine competedwith the cocaine-HEL conjugate for binding to the antibodies (FIG. 23).Additionally, at high concentrations, benzoylecgonine, a cocainemetabolite, also bound to the antibodies. None of the other compoundswere able to inhibit antibody binding to the conjugate.

Example 22 Quantification of Cocaine-Specific Antibody

Without intending to limit the invention, one method of directlyquantifying the antigen binding capacity and affinity of theantigen-specific antibodies obtained using the cocaine conjugate vaccineis disclosed. The classical immunochemical technique of equilibriumdialysis is used. Immune sera elicited by immunization with cocaine-BSAPS-5.6 and control antisera were placed inside dialysis bags (celluloseester, 25,000 MWCO, Spectrum, Los Angeles, Calif.) and dialyzed toequilibrium against a large volume containing various concentrations ofH-cocaine in PBS. This allowed measurement of the amount of cocainebound to the antibody and the amount that was unbound. Data wereanalyzed both by plotting the amount of bound cocaine as a function ofamount of total cocaine and by Scatchard plot (bound versus bound/freeantigen). As expected, the antisera contained a heterogeneous mixture ofantibodies with affinities ranging from 1×10⁻⁷ to −1×10⁻¹⁰ M. Measuredcocaine binding capacity was up to about 10 μM, indicating aconcentration of antigen-specific antibody of about 0.7 mg/ml.Therefore, immunization with the cocaine conjugate vaccine can produceantibodies with a range of useful affinities and with high cocainebinding capacities, such that a substantial proportion of the totalantibody in the circulation can react with and neutralize cocaine.

Example 23 Efficacy of Cocaine-Specific Antibody in Inhibiting CocaineDistribution In Vivo A. Inhibition of Cocaine Distribution to the Brain

To assess changes in cocaine tissue distribution caused bycocaine-specific antibody, ³H-cocaine distribution was followed inPS-5.7 cocaine-BSA-immunized mice compared to BSA-immune control mice.Immune and control immunized mice were injected with 0.5 mg/kg³H-cocaine i.v. and then decapitated at 0.5 minutes after injection.Brains, hearts and blood (plasma) were removed for subsequent analysisof tissue and plasma cocaine N concentration. Blood was collected intotubes containing sodium fluoride solution to inhibit esterases andcontaining EDTA to prevent clotting. Brains, hearts and plasma sampleswere placed into scintillation vials containing tissue solubilizer;digestion of samples occurred over 3 days at room temperature. Thesamples were decolorized and scintillation cocktail was added to eachsample. Glacial acetic acid was added to clarify the samples. After thesamples were counted in a scintillation counter, data were converted tong/g or ng/ml of tissue. Cocaine concentration in the brain tissue wassignificantly lower (n=10, p 0.05) at 0.5 minutes after injection(636.1+/−57.5 ng/g (mean+/−SEM) for cocaine-BSA-immunized vs.1052.2+/−93.85 ng/g for BSA-immunized mice).

Cocaine concentration was also measured in the plasma.Cocaine-BSA-immunized mice had significantly higher (P<0.05) to levelsof cocaine in the plasma (999.8±85.9 ng/ml) than did controlBSA-immunized mice (266.5±51.0 ng/ml). The retention of cocaine in theplasma, due to antibody binding, could also be expressed as the apparentvolume of cocaine in control (2.24±0.24 l/kg) and cocaine-BSA-immunized(0.53±0.04 l/kg) is mice. Measurement of the apparent volume ofdistribution provides a convenient way to determine whether the antibodylevels are adequate to significantly affect the distribution of cocainein vivo. Because it only requires measurement of plasma levels ofcocaine, it can also be used as a measure of antibody levels in humansfollowing cocaine challenge.

Several groups of mice were injected two times i.v. with 0.5 mg/kgcocaine to determine the ability of cocaine-specific antibody to inhibitdistribution of repeated doses of cocaine. Only the second dose ofcocaine, given 10 minutes after the initial dose, included the³H-cocaine. The antibody inhibited the distribution of the cocaineredose to the brain tissue in cocaine-BSA-immunized mice (443.6+/−48.5ng/g), compared to BSA-immunized mice (948.9+/−43.3 ng/g (n=10,p<0.001)). Thus, the inhibition of cocaine distribution after the seconddose of cocaine was similar to the inhibition of distribution after onedose.

B. Inhibition of Distribution to Cardiac Tissue

Immune and control immunized mice were anesthetized and intravenouslyinjected with 0.015 mg/kg ³H-cocaine and were decapitated 0.5 minutesafter injection. Brains, hearts and blood (plasma) samples were removedfor subsequent analysis of cocaine concentration. The concentration ofcocaine in heart tissue of cocaine-BSA immune mice at 5.7+/−0.78 ng/gwas significantly lower than that of control BSA mice at 23.4+/−4.6 ng/g(n=5, p<0.001). The inhibition of cocaine distribution to heart tissuein cocaine-immunized mice was equal to or greater than the inhibition ofcocaine distribution to brain tissue.

C. Inhibition of Cocaine Tissue Distribution after IntranasalAdministration

Effects of cocaine-specific antibody after intranasal cocaineadministration were compared to effects after intravenous cocaineadministration. In intranasal administration the kinetics ofdistribution are different from intravenous administration. Immune orcontrol mice were anesthetized and 1 mg/kg ³H-cocaine was intranasallyadministered in 50 μl PBS. Cocaine levels did not peak until 2-5 minutesafter intranasal administration, as opposed to a 15 second peak afterintravenous injection. Therefore, two minutes after cocaine injectionmice were decapitated and brains and blood (plasma) samples were removedfor subsequent analysis of cocaine concentration. In comparingintranasal cocaine administration to intravenous administration, totallevels of cocaine in the brains of control mice are fairly equal (1538ng/g intranasally versus 2260 ng/g intravenously).

The distribution of cocaine to the brain after intranasal cocaineadministration was inhibited by the presence of anti-cocaine antibody.Significant inhibition of brain distribution of cocaine was measuredafter cocaine was intranasally administered to cocaine-BSA-immune mice(708.3+/−82.8 μg/g), compared to control mice (1538.1+/−49.5 ng/g (n=5,p<0.0001)).

D. Antibody Titer

Mice with varying levels of cocaine-specific antibody were compared todetermine how antibody titer may affect the level of inhibition ofcocaine distribution. Groups of mice immunized in this study achievedtiter levels ranging from 6,000 to 256,000. 0.015 mg/kg of ³H-cocainewas administered to mice having low titer (about 6,000 to 18,000) orhigh titer (about 54,000 to 256,000) anti-cocaine antibody. Thirtyseconds after i.v. injection, mice were decapitated and brains and blood(plasma) samples were removed for analysis of cocaine distribution.

Mice with high antibody titers inhibited the distribution of cocaine tothe brain highly significantly (control mice: 26.1+/−2.0 ng/g,cocaine-immunized mice: 8.9+/−1.2 ng/g; n=10, p<0.0001). In contrast,mice with low titers displayed a reduced ability to inhibit thedistribution to the brain (control mice: 24.4+/−2.98 ng/g; cocaineimmunized mice, 15.7+/−3.4 ng/g).

E. Cocaine Metabolism

To determine whether cocaine-specific antibody alters cocaine metabolismin vivo, cocaine metabolites were analyzed over time in cocaine-immuneand control mice. Plasma samples tested were obtained as in animalexperiments described and performed in Part A of this Example. The timepoint tested for metabolite composition was 30 minutes. The method forpreparing the plasma for analysis is described above in Part A.

Plasma samples were aliquoted and non-radioactive cocaine, benzoylecgonine, and norcocaine were added in order to assist in the UVvisualization of the compounds. Samples were applied to silica TLCplates which were developed in two solvent systems: methanol,chloroform, and triethylamine (3:1:0.1); and ethyl acetate, methanol,water, and concentrated ammonia (85:10:3:1). Metabolites were identifiedby reference to control compounds run on the same plates. The bands werescraped off the plates and ³H-containing compounds were detected throughscintillation counting. From the counts obtained the amount of cocaine,benzoyl ecgonine, benzoic acid, and norcocaine as percent of totalcounts was determined. The total radioactivity in the plasma wasdetermined by scintillation counting of whole plasma. Benzoic acid isdetected as a metabolite when cocaine degrades into ecgonine methylester and benzoic acid, and so is equimolar to the ecgonine methyl estermetabolite.

The anti-cocaine antibodies appear to have minimal effects on cocainemetabolism in vivo. After 30 minutes the metabolites found are asfollows, expressed as percent of total:

Metabolite Coc-BSA Immune BSA Control Cocaine 19.66 +/− 7.5 17.31 +/−3.7 Norcocaine   5.5 +/− 0.93   3.6 +/− 0.93 Benzoic Acid 47.51 +/− 8.550.28 +/− 4.4 Benzoyl Ecgonine  27.3 +/− 0.6   29 +/− 7.2

F. Disappearance of Cocaine from Plasma

In order to determine whether cocaine-specific antibody changes the rateof disappearance of cocaine from the plasma, plasma samples collected atdifferent times after cocaine injection in cocaine-BSA-immunized animalsand in BSA-immunized animals were analyzed. Immune and control immunizedmice were injected with 1 mg/kg ³H-cocaine i.v. and then decapitated at0.5, 5 or 30 minutes after injection. Brains and blood (plasma) wereremoved for subsequent analysis for brain and plasma cocaineconcentration, percent of cocaine bound to antibody, and TLC forquantitation of cocaine and cocaine metabolites in plasma.

Plasma was analyzed as described above in Part E above for percent oftotal radioactivity in the form of cocaine and any metabolites. Plasmasamples were also analyzed for total radioactivity. The rate ofdisappearance of cocaine from the plasma of cocaine-BSA-immunized micewas compared to the rate of disappearance of cocaine from BSA-immunizedmice. In this analysis, the small fraction of norcocaine (less than 5%)was considered with the cocaine since norcocaine has CNS activity andbinds to antibody. This does not alter the results described below.

Cocaine disappears from the plasma of both groups of animals at verysimilar rates. Between 30 seconds and 30 minutes, about 80% of thecocaine had disappeared from the plasma of both groups of animals. Thedisappearance of cocaine in plasma at these times after injection wasdue to both redistribution and metabolism. Although cocaine disappearsat a similar rate in the two groups of animals, there is more cocaine inthe plasma of the cocaine-BSA-immunized mice than in plasma from theBSA-immunized mice at all times. The presence of cocaine-specificantibody did not detectably alter the elimination of cocaine.

G. Percent of Cocaine Bound to Antibody

The inhibition of distribution as shown above is possible if cocaine isbound to antibody in the animal. To determine the degree of binding ofplasma cocaine to antibody, immune and control immunized mice wereinjected with 1 mg/kg H-cocaine i.v. and then decapitated at 0.5 minutesafter injection. Blood (plasma) was removed and protein G beads wereused to capture the antibody-cocaine complexes. Protein G beads wereadded to plasma from ³H-cocaine-injected animal (with NaF to inhibitcocaine degradation) and incubated. After rinsing, each of the rinsevolumes and the beads were added to scintillation fluid. The ³H-cocainewas detected by scintillation counting. The same plasma was analyzed fordegradation of cocaine as in the metabolism assay is (Part E) above.Since the antibodies made after immunization with cocaine-BSA bind tococaine and to norcocaine, but not to the other major metabolites, asdemonstrated in the Examples, percent binding was calculated based onthe amount of cocaine and norcocaine found in the plasma sample.

In the animals which were immunized with cocaine-BSA, an average ofabout 50% of the cocaine in the plasma sample was bound to antibody.This is compared to the BSA-immunized animals, in which 3% of thecocaine was bound to antibody. The 3% value represents the background inthe assay.

H. Cocaine-CTB Hapten Carrier Elicits Effective Antibody

Cocaine-CTB PS-5.53 was injected into mice to determine whether it wasable to elicit antibodies that would alter cocaine distribution. CTBitself was injected into groups of control mice. Mice were boosted withcocaine-CTB PS-5.53 and PS-5.70 as needed until the antibody titers wereabout 54,000 or greater. The methods used for immunization and assayingcocaine-specific antibody titers are described in Examples. Mice withcocaine-specific antibody titers and control mice were injected with 0.5mg/kg H-cocaine and were decapitated 30 seconds after injection. Braintissue and plasma was isolated and analyzed for ³H-cocaine content asdescribed in part A of this Example.

The antibody produced after immunization with cocaine-CTB inhibited thedistribution of cocaine to the brain significantly. For cocaine-CTBimmunized compared to CTB-immunized mice there was significantly lesscocaine in the brain tissue (678.8 ng/g compared to 885.4 ng/g, n=6,p=0.0004 by two-tailed t-test). Likewise, the cocaine was retained inthe plasma of cocaine-CTB to a significantly greater extent than in theCTB-immunized animals. Therefore the cocaine-CTB is effective ingenerating antibody that will inhibit the distribution of cocaine to thebrain.

Example 24 Passive Transfer of Immune Immunoglobulin in Mice

Mice are immunized with PS-5-CTB using optimal immunization regimens asdescribed in the Examples. At varying times, mice are bled and thetiters of anti-cocaine antibody are assessed by ELISA. Animals withantibody titers of about 54,000 or greater are sacrificed and bled bycardiac puncture. Control mice are immunized with the carrier proteinalone. Sera from multiple mice (at least 20) are pooled and the IgGfraction is isolated by ammonium sulfate precipitation. Followingdialysis to remove the u ammonium sulfate, the level of cocaine-specificantibody in the pooled immunoglobulin fraction is quantified by ELISA.Varying amounts of immunoglobulin are administered i.p. or i.v. to naivemice. After 24 hours, the recipient mice are bled and the serum assayedto determine the level of cocaine-specific antibody. Using this method,the amount of antibody that must be transferred to achieve a given titeris determined. Groups of mice are given immune immunoglobulin and bledat varying periods of time to determine the clearance rate of theantigen-specific antibody. Other groups of mice are challenged withradiolabelled cocaine, as described in the Examples, and cocainedistribution to the brain are measured. Control mice received IgG fromcarrier-immunized mice. These experiments demonstrate the ability ofpassively transferred immune immunoglobulin to inhibit cocaine entryinto the brain.

Example 25 Passive Transfer of Immune Immunoglobulin in Humans

A pool of human donors is immunized with PS-5-CTB or other conjugates ofthe invention using optimal immunization regimens as described in theExamples. At various times, donors are bled by venipuncture and thetiters of anti-cocaine antibody are assayed by ELISA. Hyperimmune plasmafrom multiple donors is pooled and the IgG fraction is isolated by coldalcohol fractionation. The antibody preparation is buffered, stabilized,preserved and standardized as needed for hyperimmune antibodypreparations for human use. The level of anti-cocaine antibody isstandardized by ELISA or other antibody-based assay.

An appropriate dose of purified antibody is administered to patientsintramuscularly or intravenously with or without the cocaine-CTBvaccine, but not in the same anatomical site as the vaccine. Theappropriate dose is determined by assaying serum levels of recipients ina trail patient population by ELISA or other antibody-based assay at 24hours or other appropriate time point after injection of the hyperimmuneantibody preparation and/or assaying the effectiveness of differentdoses in inhibiting cocaine effects.

The passively transferred immune globulin inhibits cocaine effects inthe patients. The use of human donors, polyclonal antibody, and thelarge number of donors in the donor pool limits the chance of immuneresponse by the patients to the transferred antibody. This demonstratesthat the cocaine-CTB elicits antibodies in a donor pool that can be usedto passively immunize patients against the effects of cocaine.

Example 26 Preparation of Nicotine Conjugate Method A

To a solution of nornicotine (50 mmol) in methylene chloride was addedtriethylamine (75 mmol), followed by succinic anhydride (100 mmol). Thesolution was heated at reflux for 18 hours. The reaction mixture waswashed sequentially with 10% aqueous hydrochloric acid, saturated sodiumbicarbonate solution, brine and water. After drying (MgSO₄) and removalof the solvents under reduced pressure, the residue was purified usingsilica gel flash chromatography to furnish the desired product.

Method B

The succinylated nornicotine was then used to synthesize the nicotineconjugate PS-54 (FIG. 18). To a solution of succinylated nornicotine (5μmol) in DMF (0.1 ml), diisopropylethylamine (10 μmol) was addedfollowed by HATU (5.5 μmol). After 10 minutes, the pale yellow solutionwas added dropwise to a solution of either HEL or BSA (500 μg) in 0.1 Msodium borate buffer at pH 8.8 (0.9 ml) and the mixture stirred for 18hours at ambient temperature. The pH of the conjugate solution wasadjusted to pH 7.0 by careful addition of 0.1 M aqueous hydrochloricacid, followed by purification by dialysis against PBS. The dialysatewas filtered through a 0.2 μm filter and the level of haptenationmeasured by mass spectral analysis or UV absorbance.

Induction of Nicotine-Specific Antibody Responses

To induce an antibody response specific for a small molecule, or hapten,such as nicotine, it was necessary to link it to a T-cellepitope-containing carrier, e.g., a protein carrier. The carrier isrecognized by T-cells which are necessary for the initiation andmaintenance of antibody production by specific B cells. In this example,the carrier used was BSA. A panel of structurally distinct nicotine-BSAconjugates was produced that were linked through different parts of thenicotine molecule with several different types of linkers (FIG. 17 b).The set of different conjugates allowed the testing of differentalterations and presentations of the nicotine molecule. Since any givennicotine conjugate may induce variable amounts of antibodies whichrecognize either the free hapten (nicotine), the carrier, or theconjugate only (and do not recognize nicotine itself), screening of theconjugates was performed as in the following example.

Mice were immunized intraperitoneally with 50 μg nicotine-BSA conjugatePS-55 in complete Freund's adjuvant. A second is injection of PS-55 wasgiven on day 21 and the mice were bled on day 35. Sera were tested in anELISA for antibody binding to a conjugate of PS-55 and hen egg lysozymeprotein (HEL) and are shown in FIG. 24. These data demonstrate that thisnicotine-BSA conjugate was able to induce strong antibody responses.

Recognition of Free Nicotine

To determine whether the induced antibodies are capable of recognizingthe free nicotine molecule, a competition ELISA was performed. In thisassay, flee nicotine competes with PS-55 HEL coated to ELISA plates forthe binding of antibodies in the sera. If the antibodies that have ahigh affinity for nicotine comprise most of the antibodies binding tothe PS-55 HEL, then low concentrations of nicotine are capable ofeffectively inhibiting the antibody binding. For 3 out of 4 micedescribed above which were injected with PS-55 BSA, antibody binding toPS-55 HEL was inhibited by free nicotine (FIG. 25). Note that thepresence of antibody specific for the conjugate alone would not beexpected to interfere with the action of the anti-nicotine antibody.This indicates that antibody is present in each of these sera thatrecognizes free nicotine. The major metabolite of nicotine, cotinine,was also tested in the competition ELISA and it cannot compete withantibodies in any of the sera except at very high concentrations.

To verify that the induced antibodies were capable of recognizing thefree nicotine molecule, an RIA was used to measure specific binding to[³H]-nicotine. Immune sera from the above experiment was incubated with[³H]-nicotine and protein-G-conjugated Sepharose beads (Gammabind-GSepharose, Pharmacia), which bind IgG in the sera samples. Theantibody-bound [³H]-nicotine was isolated by centrifugation of the beadsand was detected by scintillation counting of the beads. Sera from 3 outof the 4 mice bound significantly to free [³H]-nicotine (FIG. 25).Pre-incubation of these sera with 50-fold excess unlabeled nicotinecompletely inhibited the binding of the [³H]-nicotine to theseantibodies. These data demonstrate that nicotine-carrier is conjugateshave been synthesized which induce nicotine-specific antibody responsesthat should be capable of preventing the distribution of nicotine to thebrain in vivo.

Specificity of Nicotine-Specific Antibodies

To analyze the specificity of the anti-nicotine antibodies induced bythe nicotine vaccine, sera from the mice immunized with nicotine-CTBconjugate are tested in a competition ELISA. A panel of metabolites ofnicotine and related molecules are tested at varying concentrations. Ifthe antibodies have high affinity for n the metabolite, then lowconcentrations are capable of effectively competing this assay. Therelative reactivity is expressed as the IC₅₀, the concentration of theinhibitor that decreases the ELISA signal by 50%. The followingmetabolites are tested for reactivity: nicotine glucuronide, cotinine,cotinine glucuronide, trans-3′-hydroxycotinine, trans-3′-hydroxycotinineglucuronide, nicotine 1′-N-oxide, cotinine N-oxide, and nornicotine.

Efficacy of Nicotine-Specific Antibody in Inhibiting NicotineDistribution In Vivo Inhibition of Nicotine Distribution to the Brain

To assess changes in nicotine tissue distribution caused bynicotine-specific antibody, ³H-nicotine distribution is followed innicotine-CTB-immunized mice compared to CTB-immune control mice. Immuneand control immunized mice are injected with 0.02 mg/kg ³H-nicotine i.v.and then decapitated at 0.5 minutes after injection. Brains and blood(plasma) are removed for subsequent to analysis of tissue and plasmanicotine concentration. Blood is collected into tubes containing EDTA toprevent clotting. Brains and plasma samples are placed intoscintillation vials containing tissue stabilizer; digestion of samplesoccurs over 3 days at room temperature. The samples are decolorized andscintillation is cocktail is added to each sample. Glacial acetic acidis added to clarify the samples. After the samples are counted in ascintillation counter, data are converted to ng/g or ng/ml of tissue.Nicotine concentration in the brain tissue of nicotine-CTB-immunizedmice is significantly lower after injection of ³H-nicotine than in braintissue of CTB-immunized control mice.

Example 27 Method A N′-Butyric Acid Adduct or (S)-Nicotine

To a solution of (S)-nicotine (0.031 moles) in anhydrous methanol (50ml) at ice-water temperature under argon, ethyl-4-bromobutyrate (0.0341moles) was added dropwise over 10 minutes. The resulting orange coloredsolution was allowed to warm to ambient temperature and stirred for 18hours. The solvents were removed under reduced pressure leaving a brownresidue which was precipitated with hexane to give an analytically puresample of the desired ester.

The ester (36 mg) was dissolved in methanol (3 ml) raid 1M sodiumhydroxide solution (5 ml) and stirred for 18 hours at ambienttemperature. The solvents were removed under reduced pressure and theresidue dissolved in 10% hydrochloric acid and extracted with ethylacetate. Following drying (MgSO₄) the solvents were removed underreduced pressure to yield the desired compound.

Method B N′-Valeric Acid Adduct of (S)-Nicotine

To a solution of (S)-nicotine (0.031 moles) in anhydrous methanol (50ml) at ice-water temperature under argon, 1-bromovaleric acid (0.0341moles) was added dropwise over 10 minutes. The resulting orange coloredsolution was allowed to warm to ambient temperature and stirred for 18hours. The solvents were removed under reduced pressure leaving a brownresidue which was precipitated with hexane to give an analytically puresample of the desired compound.

Method C N′-Hexanoic Acid Adduct of (S)-Nicotine

To a solution of (S)-nicotine (0.031 moles) in anhydrous methanol (50ml) at ice-water temperature under argon, 1-bromohexanoic acid (0.0341moles) was added dropwise over 10 minutes. The resulting orange coloredsolution was allowed to warm to ambient temperature and stirred for 18hours. The solvents were removed under reduced pressure leaving a brownresidue which was precipitated with hexane to give an analytically puresample of the desired compound.

Method D N′-Octanoic Acid Adduct of (S)-Nicotine

To a solution of (S)-nicotine (0.031 moles) in anhydrous methanol (50ml) at ice-water temperature under argon, the appropriate1-bromooctanoic acid (0.0341 moles) was added dropwise over 10 minutes.The resulting orange colored solution was allowed to warm to ambienttemperature and stirred for 18 hours. The solvents were removed underreduced pressure leaving a brown residue which was precipitated withhexane to give an analytically pure sample of the desired compound.

Example 28 Method A General Preparation of PS-55, PS-56, PS-57 and PS-58

To a solution of the appropriate N′-alkanoic acid analog of nicotine(6.27×10⁻⁵ moles) (from Example 26) in DMF (1.6 ml), DIEA (1.25×10⁻⁴moles) and HATU (7.53×10⁻⁵ moles) were added. After 10 minutes atambient temperature, the pale yellow solution was added to either HEL orBSA (16.5 mg) in 0.1M sodium bicarbonate, pH 8.3 (14.4 ml) and stirredfor 18 hours. The conjugate solution was purified by dialysis againstPBS at 4° C. overnight. The conjugates were analyzed using laserdesorption mass spectral analysis to determine the number of haptens.

Method B General Preparation of PS-55, PS-56, PS-57 and PS-58 with rCTBas Carrier Protein

To a solution of the appropriate N′-alkanoic acid analog of nicotine(6.27×10⁻⁵ moles) (from Example 26) in DMF (1.6 ml), DIEA (1.25×10⁻⁴moles) and HATU (7.53×10⁻⁵ moles) are added. After 10 minutes at ambienttemperature, the pale yellow solution is added to rCTB (16.6 mg) in 0.1Msodium bicarbonate, pH 8.3 (14.4 ml) and stirred for 18 hours. Theconjugate solution is purified by dialysis against PBS at 4° C.overnight. The conjugates are analyzed using laser desorption massspectral analysis to determine the number of haptens.

Example 29 Preparative-Scale Purification of rCTB

rCTB from V. cholerae supplied from SBL Vaccin AB in 0.22 M phosphate pH7.3, 0.9% NaCl buffer was diafiltered into 20 mM sodium phosphate, pH6.5. A sample was then purified using cation exchange chromatography onPharmacia SP Sepharose Fast Flow resin with Buffer A: 20 mM sodiumphosphate pH 6.5 and Buffer B: 20 mM sodium phosphate pH 6.5, 1.0 M NaClas the elution buffers. The purified fractions were analyzed bySDS-PAGE, staining with Daichi Silver Stain. The purified sample wasfiltered through a 0.22 micron filter and stored sterile at 4° C.

Example 30 Method A Analytical

Samples for analytical reverse phase HPLC(RP HPLC) were prepared by thefollowing method: 100 μl of conjugate CTB-5.200 was precipitated byadding 1.0 ml of absolute ethanol and freezing at −80° C. overnight. Theconjugate was spun at 14000 rpm for 20 minutes at 4° C. and then theethanol was decanted off and the pellet air dried. The pellet wasresuspended in 25 μl of 20% acetonitrile with 0.1% trifluoroacetic acid(TFA) and protein concentration measured by the Pierce Micro BCA assay.

The conjugate was analyzed using a C18 reverse phase column (Vydac No.218TP5215 narrow bore) 2.1×150 mm; particle size: 5μ; flow rate: 200μl/min.; Buffer A: 100% water 0.1% TFA; Buffer B: 80% acetonitrile,0.08% TFA. The gradient started at 16 B, increased to 56% B over aperiod of 50 minutes, increased to 80% B at 60 minutes, and was held for10 minutes.

Method B Semi-Preparative

Samples for RP HPLC on the semi-preparative scale were prepared asfollows: two vials of CTB-5.200 lyophile were resuspended in 20%acetonitrile 0.1% TFA, sterile filtered, and quantitated by the PierceMicro BCA. Two injections of 1.24 mg each were made on asemi-preparative RP HPLC system using a C18 column (Vydac No. 218TP1520)10×50 mm, particle size: 5 μl; flow rate: 1.8 ml/min; Buffer A: 0.1% TFAin water; Buffer B: 0.08% TFA in 80% acetonitrile. A stepwise gradientwas used as follows: 20% B for 10 minutes, 35% B for 40 minutes, 55% Bfor 5 minutes, finishing with a 5 minute wash out at 100% B. Peaks werecollected and immediately lyophilized.

Example 31 Correlation of GM1 Binding and Immunogenicity

An in vitro measurement of conjugate binding, the GM1 ELISA, wascompared to in vivo immunogenicity for a panel of cocaine-CTBconjugates. The ganglioside GM1, the natural cellular ligand for choleratoxin binding, was coated onto ELISA plates. The conjugates were thenincubated on the plates; only functional multimers of the CTB arecapable of binding to a GM1-coated plate. A cocaine-specific murineantibody pool was used to detect hapten on the bound conjugates. Thecocaine-CTB conjugates were then screened in an immunogenicity assay todetermine if they induced anti-cocaine antibodies. In screening thecocaine-CTB conjugates there was a positive correlation between GM1binding and immunogenicity (data not shown). Five out of eightcocaine-CTB conjugates that were positive in the GM1 ELISA(concentrations of less than 20 ng/ml are regarded as positiveresponses) also were positive in the immunogenicity assay (sera from 2out of 3 mice tested at a 1/900 dilution generated an O.D. of 0.900 orhigher). Most of the conjugates that were not positive in the GM1 ELISAalso were not positive in the immunogenicity assay.

Example 32 Level of Haptenation vs. Immunogenicity

The ratio of drug hapten to carrier protein in the conjugate may alterthe ability of the conjugates to stimulate production of hapten-specificantibody. The conjugation reaction was altered to produce cocaine-CTBconjugates with several different levels of haptenation. Degree ofhaptenation was calculated by analysis of mass spectrometry of theconjugates. These conjugates were screened for biological activity inimmunogenicity experiments and by mass spectrometry analysis forhaptenation levels. Conjugates were made by three different methodsusing different ratios of haptenation reagents compared to carrierprotein (Example 6: Methods G & L, Methods H & M, and Method I). Acomparison of level of haptenation and immunogenicity was made. Forthese conjugates, higher levels of haptenation produce lower quantitiesof anti-cocaine antibodies. The conjugates that had a lower range ofhaptenation produced higher anti-cocaine antibody levels. Therefore inorder to produce high anti-cocaine antibodies a certain range ofhaptenation has been determined to be advantageous.

Example 33 Induction of Cocaine Specific Antibody Response in a SecondAnimal Model

Rats were injected with cocaine-CTB PS-5.189 conjugate to determinewhether the conjugate induces cocaine-specific antibodies in a secondspecies. Wistar male rats were immunized with 10 μg of cocaine-rCTBconjugate precipitated on alum intramuscularly and again bled 14 daysafter the second injection. Sera were tested in an ELISA using platescoated with PS-5.4 conjugated to HEL (hen egg lysozyme). The response of5 individual rats per group are shown in direct ELISA (FIG. 26). Thesedata demonstrate that the cocaine-rCTB conjugates are able to induceantibody responses in rats.

To directly determine whether the antibodies generated in is rats arecapable of recognizing the free cocaine molecule, a competition ELISAwas established. Plates were coated with PS-5.4 HEL and incubated withthe anti-sera at a dilution that represents the 50% point of the curveand varying concentrations of free cocaine as competitor. If antibodywhich has a high affinity for free cocaine comprises much of theantibody that is capable of binding to cocaine-HEL, then small amountsof free cocaine will inhibit the binding of the antibody to cocaine-HEL.When cocaine-rCTB conjugate was used as an immunogen the binding ofantibodies in the rat sera were inhibited by free cocaine (FIG. 27). Themajor metabolite of cocaine, benzoylecgonine, was also tested in thecompetition ELISA and none of the sera tested are able to be competed bybenzoylecgonine. These data demonstrate that cocaine-carrier conjugatescan be synthesized which induce cocaine specific antibody responses inrats.

EQUIVALENTS

Those skilled in the art will recognize, or be able to ascertain, usingno more than routine experimentation, numerous equivalents to thespecific substances and procedures described herein. Such equivalentsare considered to be within the scope of this invention, and are coveredby the following claims.

1-87. (canceled)
 88. A hapten-carrier conjugate comprising a carrierwherein the carrier is a bacterial toxin, a product of a bacterialtoxin, a subviral, lectin, an allergen, a fragment of an allergen, amalarial protein antigen or an artificial multi-antigenic peptide,wherein the hapten is a hallucinogen, a cannabinoid, a depressant,heroin, methadone, morphine, meperidine, codeine, pentazocine,propoxyphene, ecstasy, amphetamine, phenmetrazine or methylphenidate ora derivative or a metabolite thereof, and wherein the hapten and thecarrier are linked by a branch selected from the group of chemicalmoieties identified by CJ reference number, consisting of CJ 0 Q CJ 1(CH₂)_(n)Q CJ 1.1 CO₂Q CJ 1.2 COQ CJ 2 OCO(CH₂)_(n)Q CJ 2.1 OCOCH=Q CJ2.2 OCOCH(O)CH₂ CJ 2.3 OCO(CH₂)_(n)CH₂ CJ 3 CO(CH₂)_(n)COQ CJ 3.1CO(CH₂)_(n)CNQ CJ 4 OCO(CH₂)_(n)COQ CJ 4.1 OCO(CH₂)_(n)CNQ CJ 5CH₂OCO(CH₂)_(n)COQ CJ 5.1 CH₂ OCO(CH₂)_(n)CNQ CJ 6 CONH(CH₂)_(n)Q CJ 7Y(CH₂)_(n)Q CJ 7.1 CH₂Y(CH₂)_(n)Q CJ 8 OCOCH(OH)CH₂Q CJ 8.1OCO(CH₂)_(n)CH(OH)CH₂Q CJ 9 OCOC₆H₅ CJ 10

wherein Q′ is a modified protein; and CJ 11 YCO(CH₂)nCOQ; wherein Y issulfur (S), oxygen (O), or an amine (NH), and wherein n is an integer,and wherein Q is another branch defined by a CJ reference number, or Qis the carrier.
 89. The hapten-carrier conjugate of claim 88, wherein nis an integer from 3 to
 20. 90. The hapten-carrier conjugate of claim88, wherein the hallucinogen is mescaline or LSD.
 91. The hapten-carrierconjugate of claim 88, wherein the depressant is a nonbarbiturate,methaqualone, a barbiturate, diazepam, flurazepam, phencyclidine, orfluoxetine.
 92. The hapten-carrier conjugate of claim 88, wherein thecarrier is cholera toxin B, diphtheria toxin, tetanus toxoid, pertussistoxin, filamentous hemagglutinin, Shiga toxin, pseudomonas exotoxin,ricin B subunit, abrin, sweet pea lectin, retrovirus nucleoprotein,rabies nucleoprotein, tobacco mosaic virus, cauliflower mosaic virus,vesicular stomatitis virus-nucleocapsid protein, poxvirus subunit,Semliki forest virus vector or yeast virus-like particle.
 93. Thehapten-carrier conjugate of claim 92, wherein the carrier is choleratoxin B (CTB).
 94. A therapeutic composition comprising thehapten-carrier conjugate of claim 88 and a pharmaceutically acceptablecarrier.
 95. The therapeutic composition of claim 94 further comprisingan adjuvant.
 96. The therapeutic composition of claim 95, wherein theadjuvant is alum, MF-59 or RIBI adjuvant.
 97. The therapeuticcomposition of claim 96, wherein the alum is aluminum hydroxide oraluminum phosphate.